Voltage generating circuit

ABSTRACT

A voltage generating circuit, in which the influence of offset of an amplifier on an output voltage is reduced, has first and second bipolar transistors (Q 1 , Q 2 ) having emitter terminals at the same electric potential. A base terminal of Q 1  is disposed on a collector side of Q 2 . A first resistance element connects the collector side of Q 2  with the base side of Q 2 ; and a second resistance element (R 1 ) connects a collector side of Q 1  to R 2 . A third resistance element (R 3 ) connects a base terminal of Q 2  with the electric potential of the emitter terminals. An amplifier (Al) outputs a voltage based on a voltage difference between the collector sides of Q 1  and Q 2 ; and a voltage-current converting section (MP 1 , MP 2 ) converts amplifier output into a current supplied to the connection node of R 1  and R 2 . A voltage is then output on the basis of the generated current.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation application of U.S. application Ser.No. 14/009,715, filed Oct. 3, 2013, the entirety of the contents andsubject matter of all of the above is incorporated herein by reference.

TECHNICAL FIELD

The present invention relates to a voltage generating circuit, and moreparticularly, to a technique that is effectively applied to a referencevoltage generating circuit in a semiconductor integrated circuit.

BACKGROUND ART

In a semiconductor integrated circuit such as a system LSI, a referencevoltage generating circuit for supply of a reference voltage to an A/Dconverter (ADC), a D/A converter (DAC), a regulator, a temperaturesensor and the like inside an LSI is formed. Since performances of theabove-mentioned functional sections significantly depend on the accuracyof the reference voltage, the reference voltage generating circuit needsto have low dependence on a semiconductor manufacturing process andtemperature. Further, the reference voltage generating circuit needs tooperate at a low power supply voltage. According to these needs, a bandgap reference (hereinafter, referred to as “BGR”) circuit that generatesvoltage on the basis of a band gap value of silicon is widely used forthe reference voltage generating circuit.

NPL 1 and PTL 1 disclose an example of a BGR circuit in the related art.Further, PTL 2 discloses a BGR circuit that copes with the low powersupply voltage.

It is known that the temperature dependence of a base-emitter voltage ofa bipolar transistor (also referred to as a bipolar junction transistor(BJT)) that is a basic component of the BGR circuit is non-linear (forexample, see NPL 2). NPL 3 discloses a BGR circuit that reducesnon-linear temperature dependence of an output voltage. Further, NPLs 4to 6 disclose an example of a correcting circuit or the like forcorrection of non-linear temperature dependence with respect to the BGRcircuit disclosed in PTL 1. Further, NPL 7 discloses a method ofcorrecting a temperature characteristic by a current (I_(PTAT) ²) thatis proportional to the square of the absolute temperature.

CITATION LIST Patent Literature

-   [PTL 1] U.S. Pat. No. 3,887,863-   [PTL 2] U.S. Pat. No. 6,160,391

Non Patent Literature

-   [NPL 1] Kuijk, K. E, “A precision reference voltage source”, IEEE    JOURNAL OF SOLID-STATE CIRCUITS, VOL. sc-8, No. 3, June 1973-   [NPL 2] Tsividis, Y. P., “Accurate analysis of temperature effects    in Ic-VBE characteristics with application to band gap reference    sources”, IEEE JOURNAL OF SOLID-STATE CIRCUITS, VOL. sc-15, No. 6,    December 1980-   [NPL 3] P. Malcovati, “Curvature-Compensated BiCMOS Band gap with    1-V Supply Voltage”, IEEE JOURNAL OF SOLID-STATE CIRCUITS, VOL.    sc-36, No. 7, July 2001-   [NPL 4] Pease, R. A., “A new Fahrenheit temperature sensor”, IEEE    JOURNAL OF SOLID-STATE CIRCUITS, VOL. sc-19, No. 6, December 1984-   [NPL 5] Paul, R. Patra, A., “A temperature-compensated band gap    voltage reference circuit for high precision applications”, India    Annual Conference, 2004, Proceedings of the IEE INDICON 2004, First    Publication Date: 20-22 Dec. 2004-   [NPL 6] Paul, R. Patra, A. Baranwal, S. Dash, K., “Design of    second-order sub-band gap mixed-mode voltage reference circuit for    low voltage applications”, VLSI Design, 2005, 18^(th) International    Conference on Issue Date: 3-7 Jan. 2005-   [NPL 7] Sundar, Siddharth, “A low power high power supply rejection    ratio band gap reference for portable applications”, Massachusetts    Institute of Technology, 2008

DISCLOSURE OF THE INVENTION Problems that the Invention is to Solve

In recent years, a BGR circuit in which the influence of offset of anamplifier that is a component of the BGR circuit or the influence ofmismatching of a current mirror circuit that is another component of theBGR circuit is small, its operation is performed at a power supplyvoltage of 1 V or lower and voltage variation is small in a widetemperature range (for example, −55° C. to 160° C.) has been demanded.

However, the present inventors considered that the BGR circuit in therelated art had, for example, the following problems.

A BGR circuit disclosed in NPL 1 that is a classic configuration amongBGR circuits has a characteristic that the BGR circuit is influenced byoffset of an amplifier and the variation of an output voltage is large.Further, the output voltage is about 1.2 V, and thus, it is furtherdifficult to lower a power supply voltage of the BGR circuit. Inaddition, with respect to the temperature dependence, since only thetemperature correction that is proportional to the absolute temperatureis performed, it is difficult to suppress the variation of the outputvoltage in a wide temperature range.

A BGR circuit disclosed in PTL 1 that is similarly a classicconfiguration among the BGR circuits is less influenced by offset of anamplifier, compared with the BGR circuit disclosed in NPL 1. However, anoutput voltage is 1.2 V, and thus, it is difficult to lower a powersupply voltage. Further, with respect to the temperature dependence,since only the temperature correction that is proportional to theabsolute temperature is performed, it is difficult to suppress thevariation of the output voltage in a wide temperature range.

A BGR circuit disclosed in PTL 2 has a circuit configuration in whichthe BGR circuit disclosed in NPL 1 is used as a base and its operationmay be performed at a power supply voltage of 1 V or lower. However, ina similar way to the BGR circuit in NPL 1, dependence of the outputvoltage on offset of an amplifier and the temperature dependence thereofare high.

A BGR circuit disclosed in NPL 3 has a configuration in which thenon-linear temperature dependence of the BGR circuit in PTL 2 isreduced, in which a low power supply voltage may be achieved and thetemperature dependence may be reduced. However, dependence on offset ofan amplifier is high.

A temperature correction method disclosed in NPL 7 is a correctionmethod that uses a current I_(PTAT) ² that changes from the absolutetemperature 0 K, in which a temperature characteristic is not easilyimproved in a desired temperature range to be corrected. Although thetemperature correction method in NPL 7 is employed, if an I_(PTAT) ²current generating circuit disclosed in NPLs 4 to 6 is used forgenerating the current I_(PTAT) ², the size of the circuit and thenumber of elements become large, which complicates a circuitconfiguration and is not suitable for a low power supply voltage.

An object of the invention is to provide a voltage generating circuit inwhich the influence of offset of an amplifier that is a component on anoutput voltage is reduced.

Another object of the invention is to provide a voltage generatingcircuit that is capable of being operated at a low power supply voltage.

Still another object of the invention is to provide a voltage generatingcircuit in which the temperature dependence of an output voltage islowered.

The above and other objects and novel features of the invention willbecome apparent from the following description and the accompanyingdrawings.

Means for Solving the Problems

A summary of a representative embodiment of the invention disclosedherein will be briefly described as follows.

That is, a voltage generating circuit according to the representativeembodiment of the invention includes a current generating section togenerate a current obtained by adding a current based on a voltagedifference between base-emitter voltages of two bipolar transistors anda current based on a forward voltage of a PN junction. The currentgenerating section includes: a first bipolar transistor that includes anemitter terminal disposed on a first electric potential node side; asecond bipolar transistor that has an emitter area larger than anemitter area of the first bipolar transistor, includes an emitterterminal at the same electric potential as in the emitter terminal ofthe first bipolar transistor and includes a base terminal disposed on acollector side of the first bipolar transistor; a first resistanceelement that is disposed on the collector side of the first bipolartransistor at one end thereof and is disposed on a base side of thefirst bipolar transistor at the other end thereof; a second resistanceelement that is disposed on a collector side of the second bipolartransistor at one end thereof and is connected to the other end of thefirst resistance element at the other end thereof; a third resistanceelement that is provided between a base terminal of the first bipolartransistor and the first electric potential node; an amplifier thatreceives, as inputs, voltages on the collector sides of two bipolartransistors and outputs a voltage based on a voltage difference betweentwo input voltages; and a voltage-current converting section thatreceives, as an input, the output voltage of the amplifier, converts thereceived voltage into a current and supplies the converted current to aconnection node of the first resistance element and the secondresistance element. The voltage generating circuit converts thegenerated current into voltage to be output.

Effects of the Invention

Effects achieved by the representative embodiment of the inventiondisclosed herein are briefly described as follows.

That is, according to the voltage generating circuit of the invention,the influence of offset of an amplifier that is a component on an outputvoltage is reduced, and its operation may be performed at a low powersupply voltage.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram illustrating an example of a reference voltagegenerating circuit according to a first embodiment.

FIG. 2 is a circuit diagram illustrating an example of a specificconfiguration of the reference voltage generating circuit according tothe first embodiment.

FIG. 3 is a circuit diagram illustrating an example of a BGR corecircuit 10 in a reference voltage generating circuit 1.

FIG. 4 is a circuit diagram illustrating an example of an analysis BGRcore circuit reviewed on the basis of NPL 1.

FIG. 5 is a diagram illustrating an example of an analysis BGR corecircuit reviewed on the basis of PTL 1.

FIG. 6 is a diagram quantitatively illustrating input offset voltagedependence of an output voltage V_(BGR).

FIG. 7 is an enlarged view of FIG. 6.

FIG. 8 is a diagram illustrating simulation results of respective BGRcore circuits.

FIG. 9 is a diagram illustrating non-linear dependence of a base-emittervoltage VBE on temperature.

FIG. 10 is a diagram illustrating a principle of a method of correctinga non-linear temperature characteristic by the reference voltagegenerating circuit 1.

FIG. 11 is a diagram illustrating a correction principle of a non-linearcharacteristic for a BGR circuit reviewed on the basis of PTL 1.

FIGS. 12A and 12B are diagrams illustrating a simulation result of thetemperature dependence of a reference voltage generating circuit.

FIGS. 13A to 13D are diagrams illustrating an example of layouts ofbipolar transistors Q1 and Q2 in the BGR core circuit 10.

FIGS. 14A and 14B are circuit diagrams illustrating an example of anamplifier Al of the reference voltage generating circuit 1.

FIG. 15 is a circuit diagram illustrating an example of the referencevoltage generating circuit 1 that includes a start-up circuit.

FIG. 16 is a diagram illustrating a configuration example of a circuitin which an LPF (low pass filter) is inserted in a power supply line(Vcc).

FIGS. 17A to 17D are diagrams illustrating an example of a system towhich a reference voltage generating circuit 1 is applied.

FIG. 18 is a block diagram illustrating an example of a semiconductorintegrated circuit device to which the reference voltage generatingcircuit 1 is applied.

FIG. 19 is a circuit diagram illustrating an example of a referencevoltage generating circuit according to a second embodiment.

FIG. 20 is a diagram illustrating a principle of a method of correctinga non-linear temperature characteristic by a reference voltagegenerating circuit 2.

FIG. 21 is a circuit diagram illustrating an example of a referencevoltage generating circuit according to a third embodiment.

FIG. 22 is a diagram illustrating a principle of a method of correctinga non-linear temperature characteristic by a reference voltagegenerating circuit 3.

FIG. 23 is a circuit diagram illustrating an example of a referencevoltage generating circuit according to a fourth embodiment.

FIG. 24 is a diagram illustrating a principle of a method of correctinga non-linear temperature characteristic by a reference voltagegenerating circuit 4.

FIG. 25 is a circuit diagram illustrating an example of a referencevoltage generating circuit according to a fifth embodiment.

FIG. 26 is a diagram illustrating a principle of a method of correctinga non-linear temperature characteristic by a reference voltagegenerating circuit 5.

FIG. 27 is a circuit diagram illustrating an example of a referencevoltage generating circuit according to a sixth embodiment.

FIG. 28 is a circuit diagram illustrating an example of a BGR corecircuit according to a seventh embodiment.

FIG. 29 is a circuit diagram illustrating an example of a BGR corecircuit that includes a voltage generating section that generates avoltage (VPTAT) that is proportional to the absolute temperature.

FIG. 30 is a block diagram illustrating an example of a semiconductorintegrated circuit device to which a reference voltage generatingcircuit that includes a BGR core circuit 10E and a non-linear correctingcircuit is applied.

FIG. 31 is a circuit diagram illustrating an example of a BGR corecircuit according to an eighth embodiment.

FIG. 32 is a circuit diagram illustrating an example of a BGR corecircuit according to a ninth embodiment.

FIG. 33 is a circuit diagram illustrating another example of a BGR corecircuit that includes a voltage generating section that generates avoltage (VPTAT) that is proportional to the absolute temperature.

FIG. 34 is a circuit diagram illustrating an example of a BGR corecircuit according to a tenth embodiment.

FIG. 35 is a circuit diagram illustrating an example of a BGR corecircuit according to an eleventh embodiment.

FIG. 36 is a circuit diagram illustrating an example of a BGR corecircuit according to a twelfth embodiment.

FIG. 37 is a circuit diagram illustrating an example of a BGR corecircuit according to a thirteenth embodiment.

FIG. 38 is a circuit diagram illustrating an example of an amplifier A3of a BGR core circuit 10L.

FIG. 39 is a circuit diagram illustrating an example of a BGR corecircuit according to a fourteenth embodiment.

FIG. 40 is a circuit diagram illustrating an example of a BGR corecircuit according to a fifteenth embodiment.

FIG. 41 is a circuit diagram illustrating an example of a BGR corecircuit according to a sixteenth embodiment.

FIG. 42 is a circuit diagram illustrating an example of a BGR corecircuit according to a seventeenth embodiment.

FIG. 43 is a circuit diagram illustrating an example of a BGR corecircuit according to an eighteenth embodiment.

FIG. 44 is a circuit diagram illustrating an example of a referencevoltage generating circuit according to a nineteenth embodiment.

FIGS. 45A to 45D are diagrams illustrating a principle of a method ofcorrecting a non-linear temperature characteristic by a referencevoltage generating circuit 7.

FIG. 46 is a circuit diagram illustrating an example of a referencevoltage generating circuit according to a twentieth embodiment.

FIG. 47 is a circuit diagram illustrating an example of a referencevoltage generating circuit according to a twenty first embodiment.

FIG. 48 is a circuit diagram illustrating an example of a referencevoltage generating circuit according to a twenty second embodiment.

BEST MODE FOR CARRYING OUT THE INVENTION

1. Summary of the Embodiments

First, the outlines of representative embodiments of the inventiondisclosed herein will be described. In the outlines of therepresentative embodiments, reference numerals in parentheses in thedrawings merely illustrate that components given the reference numeralsare included in the concept of the components.

[1] (BGR core circuit (FIG. 2, FIG. 34, FIG. 40 and the like))

A voltage generating circuit (1) includes: a current generating section(Q1, Q2, R1, R2, R3, A1, MP1 and MP2) that generates a current obtainedby adding a current based on a voltage difference (ΔVBE) betweenbase-emitter voltages of two bipolar transistors (Q1, Q2) havingdifferent emitter areas and a current based on a forward voltage of a PNjunction, and an output section (R4) that converts an input current intoa voltage and outputs the converted voltage. The current generatingsection includes a first bipolar transistor (Q2) that includes anemitter terminal disposed on a first electric potential node (powersupply Vcc node/ground node) side; a second bipolar transistor (Q1) thathas an emitter area larger than an emitter area of the first bipolartransistor, includes an emitter terminal at the same electric potentialas in the emitter terminal of the first bipolar transistor and includesa base terminal disposed on a collector side of the first bipolartransistor; a first resistance element (R2) that is disposed on thecollector side of the first bipolar transistor at one end thereof and isdisposed on a base side of the first bipolar transistor at the other endthereof; a second resistance element (R1) that is disposed on acollector side of the second bipolar transistor at one end thereof andis connected to the other end of the first resistance element at theother end thereof; a third resistance element (R3) that is providedbetween a base terminal of the first bipolar transistor and the firstelectric potential node; an amplifier (A1) that receives, as inputs, avoltage on the collector side of the first bipolar transistor and avoltage on the collector side of the second bipolar transistor andoutputs a voltage based on a voltage difference between two inputvoltages; and a voltage-current converting section (MP1, MP2) thatreceives, as an input, the output voltage of the amplifier, converts thereceived voltage into a current and supplies the converted current to aconnection node (node of a voltage V3) of the first resistance elementand the second resistance element and to the output section.

In the voltage generating circuit according to [1], by using the currentgenerating section having the above configuration, it is possible toreduce the influence of offset of the amplifier on the current based onthe voltage difference between the base-emitter voltages of the firstbipolar transistor and the second bipolar transistor, and thus, it ispossible to reduce the influence of the offset of the amplifier on theoutput voltage generated by the voltage generating section.

The BGR circuits disclosed in PTL 1 and NPL 1 as described above have aconfiguration in which a voltage VPTAT that is proportional to theabsolute temperature (hereinafter, may also be referred to as “PTAT”) isadded to a base-emitter voltage VBE of the bipolar transistor to cancela coefficient (linear coefficient) that is proportional to thetemperature. Thus, considering that VBE is about 0.6 V, the outputvoltage becomes about 1.2 V, and thus, the power supply voltage is notsuitable for a low power supply voltage operation and a low outputvoltage of 1 V or lower, for example. On the other hand, in the voltagegenerating circuit according to [1], since the current that flows in thethird resistance element, based on the base-emitter voltage VBE of thefirst bipolar transistor, and the current (PTAT current) based on thevoltage difference are added to cancel a coefficient that isproportional to the temperature and the added current is converted intoa voltage to be output, it is possible to achieve a low power supplyvoltage operation and a low output voltage. Further, with respect to theabove configuration of the current generating section, by providing thethird resistance element between the base terminal of the first bipolartransistor and the first electric potential node, it is possible toeasily generate the current based on the voltage difference between thebase-emitter voltages.

[2] (BGR Core Circuit with R5 (FIG. 2, FIG. 42, FIG. 43 and the Like))

In the voltage generating circuit according to [1], the currentgenerating section includes a resistance element (R5) between theemitter terminal of the first bipolar transistor and the first electricpotential node.

According to this configuration, it is possible to increase the commoninput voltages of the amplifier by the resistance element.

[3] (BGR Core Circuit with R7 (FIG. 35, FIG. 36, FIG. 41, FIG. 42))

In the voltage generating circuit according to [1] or [2], the currentsupply to the connection node of the first resistance element and thesecond resistance element from the voltage-current converting section isperformed through a resistance element (R7).

According to this configuration, it is possible to decrease the commoninput voltages of the amplifier by the resistance element.

[4] (Voltage is Divided to be Input to Amplifier (BGR Core Circuit 10L)(FIG. 37))

In the voltage generating circuit according to any one of [1] to [3],two voltages that are input to the amplifier include a voltage obtainedby dividing a voltage of a collector terminal of the first bipolartransistor and a voltage obtained by dividing a voltage of a collectorterminal of the second bipolar transistor.

According to this configuration, it is possible to decrease the commoninput voltages of the amplifier, and thus, it is possible to provide aPMOS differential input amplifier, for example, as the amplifier whichmakes the designing easy.

[5] (Voltage-Current Converting Section Having Source DegenerationConfiguration (FIG. 39))

In the voltage generating circuit according to any one of [1] to [4],the voltage-current converting section includes: a first MOS transistor(MP1) that is connected to a second electric potential node (groundnode/power supply Vcc node) having a different electric potential fromthe first electric potential node through a resistance element (R16) ata source terminal thereof and is connected to the connection node of thefirst resistance element and the second resistance element at a drainterminal thereof; and a second MOS transistor (MP2) that is connected tothe second electric potential node through a resistance element (R17) ona source side thereof and is connected to an input side of the outputsection on a drain side thereof, and the output voltage of the amplifieris input to gate terminals of the first MOS transistor and the secondMOS transistor.

According to this configuration, it is possible to reduce mismatching ofa current of the first MOS transistor and a current of the second MOStransistor by the degeneration resistances connected to the respectivesource sides of the first MOS transistor and the second MOS transistor.

[6] (BGR Core Circuit Capable of Independently Generating IPTAT Current(FIG. 28, FIG. 29, and FIGS. 31 to 33))

A voltage generating circuit (10D to 10H) according to anotherrepresentative embodiment of the invention includes: a currentgenerating section (MP1, MP2, MP5, R1, R2, Q1, Q2) that generates afirst current based on a voltage difference between base-emittervoltages of two bipolar transistors having different emitter areas, andan output section that generates a second current based on a forwardvoltage of a PN junction on the basis of the first current and generatesa voltage on the basis of the first current and the second current tooutput the generated voltage. The current generating section includes afirst bipolar transistor (Q2) that includes an emitter terminal disposedon a first electric potential node side; a second bipolar transistor(Q1) that has an emitter area larger than an emitter area of the firstbipolar transistor, includes an emitter terminal at the same electricpotential as in the emitter terminal of the first bipolar transistor andincludes a base terminal disposed on a collector side of the firstbipolar transistor; a first resistance element (R2) that is disposed onthe collector side of the first bipolar transistor at one end thereofand is disposed on a base side of the first bipolar transistor at theother end thereof; a second resistance element (R1) that is disposed ona collector side of the second bipolar transistor at one end thereof andis connected to the other end of the first resistance element at theother end thereof; an amplifier (A1) that receives, as inputs, a voltageon the collector side of the first bipolar transistor and a voltage onthe collector side of the second bipolar transistor and outputs avoltage based on a voltage difference between two voltages; and avoltage-current converting section (MP1, MP2) that receives, as aninput, the output voltage of the amplifier, converts the receivedvoltage into a current and supplies the converted current to aconnection node (node of electric potential V3) of the first resistanceelement and the second resistance element and to the output section.

According to this configuration, in a similar way to [1], it is possibleto reduce the influence of the offset of the amplifier on the outputvoltage, and to achieve a low power supply voltage operation and a lowoutput voltage. Further, the following effect is achieved. For example,in the voltage generating circuit according to [1], the currentgenerating section generates the current (the first current in [6])based on the voltage difference between the base-emitter voltages of twobipolar transistors having the different emitter areas and the current(the second current in [6]) based on the forward voltage of the PNjunction and outputs the current obtained by adding two currents, but inthe voltage generating circuit according to [6], the current generatingsection outputs the first current. That is, according to the voltagegenerating circuit according to [6], it is possible to independentlyoutput the current (the first current) that is proportional to theabsolute temperature, and to easily generate the PTAT voltage.

[7] (Configuration of Output Stage of BGR Core Circuit 10D (FIG. 28))

In the voltage generating circuit according to [6], the output sectionincludes: a voltage generating section (Q4) that is connected to thefirst electric potential node at one end thereof and generates a voltagebased on the forward voltage of the PN junction on the basis of acurrent that is input to the other end thereof; a third resistanceelement (R9) that is connected to the first electric potential node atone end thereof; and a fourth resistance element (R8) that is providedbetween the other end side of the voltage generating section and theother end side of the third resistance element, and the first current issupplied to each node to which the fourth resistance element isconnected.

According to this configuration, since the current based on the forwardvoltage and the first current flow in the third resistance element togenerate the output voltage, it is easy to achieve a low power supplyvoltage operation and a low output voltage.

[8] (Configuration of Output Stage of BGR Core Circuit 10 and the Like(FIG. 2 and the Like))

In the voltage generating circuit according to any one of [1] to [5],the output section is a fourth resistance element (R4) that is connectedto the first electric potential node at one end thereof and receives aninput of a current at the other end thereof.

According to this configuration, it is possible to easily generate theoutput voltage.

[9] (BGR Core Circuit that Uses NPN Bipolar Transistor (FIG. 2 and theLike))

In the voltage generating circuit according to any one of [1] to [8],the first bipolar transistor and the second bipolar transistor are NPNbipolar transistors.

[10] (BGR Core Circuit that Uses PNP Bipolar Transistor (FIGS. 40 to43))

In the voltage generating circuit according to any one of [1] to [8],the first bipolar transistor and the second bipolar transistor are PNPbipolar transistors.

[11] (BGR core circuit and temperature correcting circuit (FIG. 2 andthe like))

In the voltage generating circuit according to any one of [1] to [10],the voltage generating circuit further includes: a correcting circuit(20, 20A, 20B) that generates a correcting current (I_(COMP)) based on adifference between the voltage (V_(BGR)) generated by the output sectionand the forward voltage of the PN junction and feeds back the correctingcurrent to the current generating section.

In the voltage generating circuit according to [1], the current thatflows in the third resistance element, based on the base-emitter voltageVBE of the first bipolar transistor, and the current (PTAT current)based on the voltage difference are added to cancel the coefficient thatis proportional to the temperature and the added current is convertedinto the output voltage to improve the temperature characteristic of theoutput voltage. However, as described above, since the temperaturedependence of the base-emitter voltage is non-linear, the output voltagehas the non-linear temperature dependence. Thus, in the voltagegenerating circuit according to [11], the correcting current having anon-linear temperature characteristic is generated according to thedifference between the output voltage of the voltage generating sectionand the forward voltage of the PN junction, and is fed back to thecurrent generating section to improve the non-linear temperaturedependence of the output current of the current generating section.Thus, it is possible to improve the non-linear temperature dependence ofthe output voltage, and to reduce the variation of the output voltage ina wide temperature range. Further, by generating the current based onthe difference between two voltages (output voltage and forward voltage)having the temperature dependence, it is possible to generate acorrecting current that is changed in a temperature range where thetemperature characteristic is to be corrected. According to thisconfiguration, it is easy to perform correction compared with a casewhere the temperature characteristic is corrected using the PTAT currentthat uses the absolute temperature 0 K as a starting point and a PTAT2current (current that is proportional to the square of the absolutetemperature).

[12] (Specific Configuration of Correcting Circuit (FIG. 2, FIG. 21,FIG. 23 and FIG. 25))

In the voltage generating circuit according to [11], the correctingcircuit includes: a third bipolar transistor (Q3) that is connected tothe first electric potential node through a fifth resistance element(R6) at an emitter terminal thereof and is connected to an output sideof the voltage generating section at a base terminal thereof; and acurrent mirror section (MP3, MP4) that outputs a current based on acurrent that flows in a collector terminal of the third bipolartransistor.

According to this configuration, it is possible to easily generate thecorrecting current.

[13] (Feedback Destination of Correcting Current is R3 (FIG. 19, FIG.21))

In the voltage generating circuit according to [11] or [12], thecorrecting current is fed back to the third resistance element.

According to this configuration, the feedback of the correcting currentto the current generating section becomes easy.

[14] (Feedback Destination of Correcting Current is R5 (FIG. 2, FIG.27))

In the voltage generating circuit according to [11] or [12], the emitterterminal of the first bipolar transistor is connected to the firstelectric potential node through a resistance element (R5), and thecorrecting current is fed back to the emitter terminal of the firstbipolar transistor.

According to this configuration, the feedback of the correcting currentto the current generating section becomes easy, and it is possible toincrease the common input voltages to the amplifier by the resistanceelement.

[15] (Feedback Destination of Correcting Current is Electric PotentialVB Side (FIG. 23))

In the voltage generating circuit according to [11] or [12], thecorrecting current is fed back to the one end of the second resistanceelement.

According to this configuration, the feedback of the correcting currentto the current generating section becomes easy.

[16] (Feedback Destination of Correcting Current is Resistance R4 (FIG.25))

In the voltage generating circuit according to [8], the voltagegenerating circuit further includes: a correcting circuit that generatesa correcting current based on a difference between the voltage generatedby the output section and the forward voltage of the PN junction andfeeds back the correcting current to the fourth resistance element (R4).

According to this configuration, the feedback of the correcting currentto the voltage generating section becomes easy.

[17] (Addition of Voltage Follower A2 (FIG. 2 and the Like))

In the voltage generating circuit according to [12], the correctingcircuit further includes a buffer circuit (A2) that receives the outputvoltage of the voltage generating section as an input and buffers thereceived voltage to output the result to the base terminal of the thirdbipolar transistor.

According to this configuration, it is possible to prevent the influenceof the voltage generating section on the output voltage due to a basecurrent of the third bipolar transistor.

[18] (Another Embodiment of Current Mirror Section (FIG. 23))

In the voltage generating circuit according to [12] or [17], the currentmirror section is a low voltage current mirror circuit (MP3, MP4, MN3,MN4).

According to this configuration, it is possible to achieve a low powersupply voltage of the correcting circuit.

[19] (BGR Core Circuit (Including Output of 1.2 V) and Non-LinearCorrecting Circuit (FIG. 44, FIG. 46, FIG. 47, FIG. 48, FIG. 2 and theLike))

A voltage generating circuit (1 to 9, 11) according to anotherrepresentative embodiment of the invention includes: a voltagegenerating section (10, 10A to 10Q, 71, 75) that generates a voltageobtained by adding a voltage difference between base-emitter voltages oftwo bipolar transistors (Q1, Q2) that are operated at different currentdensities and a forward voltage of a PN junction at a predeterminedratio and outputs the result; and a correcting circuit (20, 20A, 20B)that generates a correcting current (I_(COMP)) based on a differencebetween the voltage generated by the voltage generating section and theforward voltage of the PN junction and feeds back the correcting currentto the voltage generating section.

According to this configuration, in a similar way to [11], it ispossible to improve the non-linear temperature dependence of the outputvoltage, and to reduce the variation of the output voltage in a widetemperature range. Further, it is easy to perform correction comparedwith a case where the temperature characteristic is corrected using thePTAT current that uses the absolute temperature 0 K as a starting pointand a PTAT² current (current that is proportional to the square of theabsolute temperature).

[20] (Non-Linear Correcting Circuit Corresponding to Output of 1.2 V(FIG. 44 and FIG. 46))

In the voltage generating circuit according to [19], the correctingcircuit includes: a first bipolar transistor (Q5) that is connected to afirst electric potential node (ground node) through a first resistanceelement (R6, R62) at an emitter terminal thereof and is diode-connected;a second bipolar transistor (Q7) that is connected to a collector sideof the first bipolar transistor at an emitter terminal thereof and isconnected to an output side of the voltage generating section at acollector terminal and a base terminal thereof that are diode-connected;and a current output section (Q6, Q8, MP1, MP2) that outputs a currentbased on a current that flows in the first resistance element.

According to this configuration, as the first bipolar transistor and thesecond bipolar transistor are stacked at two stages, even in a casewhere the output voltage of the voltage generating section is about 1.2V, for example, it is easy to generate the correcting current.

[21] (Non-Linear Correcting Circuit Corresponding to Output of 1.2 V(FIG. 47))

In the voltage generating circuit according to [19], the correctingcircuit includes: a first bipolar transistor (Q9) that is connected to afirst electric potential node through a first resistance element (R6) atan emitter terminal thereof and is diode-connected; a second bipolartransistor (Q10) that is connected to a collector side of the firstbipolar transistor at an emitter terminal thereof and is connected to anoutput side of the voltage generating section at a base terminalthereof; and a current mirror circuit (MP11, MP12) that outputs acurrent based on a current that flows on a collector side of the secondbipolar transistor.

According to this configuration, as the first bipolar transistor and thesecond bipolar transistor are stacked at two stages, even in a casewhere the output voltage of the voltage generating section is about 1.2V, for example, it is easy to generate the correcting current.

[22] (BGR Core Circuit 71 Having Output of 1.2 V (FIG. 44, FIG. 46 andFIG. 47))

In the voltage generating circuit according to any one of [19] to [21],the voltage generating section includes: a third bipolar transistor (Q2)that is connected to the first electric potential node through a secondresistance element (R22) at a collector terminal thereof; a fourthbipolar transistor (Q1) that has an emitter area larger than the emitterarea of the third bipolar transistor and is connected to the firstelectric potential node through a third resistance element (R21) at acollector terminal thereof; a fourth resistance element (R20) that isprovided between an emitter terminal of the third bipolar transistor andan emitter terminal of the fourth bipolar transistor; and a fifthresistance element (R23) that is provided between the emitter terminalof the second bipolar transistor and a second electric potential node,and the correcting current is fed back to the fifth resistance element.

According to this configuration, even with respect to the BGR circuitthat outputs about 1.2 V, it is possible to easily realize correction ofthe non-linear temperature characteristic.

[23] (BGR Core Circuit and Temperature Correcting Circuit (MOSTr) (FIG.27))

In the voltage generating circuit (6) according to [1] to [10], thevoltage generating circuit further includes: a correcting circuit (20C)that generates a correcting current (I_(COMP)) based on a differencebetween the voltage generated by the output section (10) and agate-source voltage of a MOS transistor (MN5, MN6) that is operated in asub threshold region and feeds back the correcting current to thecurrent generating section.

Since a characteristic of the sub threshold region of the MOS transistoris a characteristic that is close to an I_(C)−V_(BE) characteristic ofthe bipolar transistor, according to the voltage generating circuitaccording to [23], by generating the current based on the differencebetween two voltages (output voltage and V_(GS) voltage) having thetemperature dependence, it is possible to generate a correcting currentthat is changed in a temperature range where the temperaturecharacteristic is to be corrected. Thus, in a similar way to [11] or thelike, it is possible to improve the non-linear temperature dependence ofthe output voltage, and to reduce the variation of the output voltage ina wide temperature range. Further, it is easy to perform correctioncompared with a case where the temperature characteristic is correctedusing the PTAT current that uses the absolute temperature 0 K as astarting point and a PTAT² current (current that is proportional to thesquare of the absolute temperature). Further, since the bipolartransistor is not used in the correcting circuit, it is possible torealize the correcting circuit in a CMOS process.

[24] (Specific Configuration of Temperature Correcting Circuit (MOSTr))

In the voltage generating circuit according to [23], the correctingcircuit includes: a first MOS transistor (MN 6) that includes a gateterminal disposed on an output side of the output section; a fourthresistance element (R6) that is connected to the first electricpotential node at one end thereof; one or plural of second MOStransistors (MN5) that are provided between a source terminal of thefirst MOS transistor and the other end of the fourth resistance elementand include a gate terminal and a drain terminal that are at the sameelectric potential; and a current mirror section (MP3, MP4) that outputsa current based on a current that flows on a drain side of the first MOStransistor.

According to this configuration, for example, by adjusting the number ofstages of the second MOS transistor, it is possible to operate the MOStransistor in the sub threshold region, and to easily generate thecorrecting current.

2. Further Detailed Description of the Embodiments

The embodiments will be described in detail.

First Embodiment

FIG. 1 is a block diagram illustrating an example of a reference voltagegenerating circuit according to a first embodiment.

A reference voltage generating circuit 1 shown in FIG. 1 includes avoltage generating circuit (hereinafter, referred to as a BGR corecircuit) 10 that generates and outputs a reference voltage V_(BGR), anda non-linear correcting circuit (hereinafter, simply referred to as acorrecting circuit) 20 that generates a correcting current forcorrecting a temperature characteristic of the reference voltage V_(BGR)according to the reference voltage V_(BGR) and feeds back the result tothe BGR core circuit.

FIG. 2 is a circuit diagram illustrating an example of a specificconfiguration of the reference voltage generating circuit 1. Althoughthere is no particular limitation, the reference voltage generatingcircuit 1 shown in FIG. 2 is formed on a single semiconductor substratemade of single crystal silicon or the like by a known CMOS integratedcircuit manufacturing technique.

A BGR core circuit 10 shown in FIG. 2 generates, by a current generatingsection 101, a current obtained by adding a current based on a voltagedifference (ΔVBE) of base-emitter voltages of two bipolar transistors Q1and Q2 having different emitter areas and a current based on abase-emitter voltage VBE2 of the bipolar transistor Q2, and converts thegenerated current into a voltage V_(BGR) for output by a voltage outputsection 102.

The current generating section 101 includes NPN bipolar transistors Q1and Q2, resistances R1, R2, R3 and R5, a differential amplifier A1, andP-channel MOS transistors MP1 and MP2, for example. Further, the voltageoutput section 102 includes a resistance R4, for example. Connectionrelationships of the respective elements are as follows.

The bipolar transistors Q1 and Q2 are connected in common at emitterterminals thereof. The emitter area of the bipolar transistor Q1 is setto be n (n is an integer of 2 or greater) times larger than that of thebipolar transistor Q2. That is, when the same current flows in thebipolar transistors Q1 and Q2, the emitter current density of thebipolar transistor Q2 is set to be n times the emitter current densityof the transistor Q1. The resistance R1 is connected to a base terminalof the bipolar transistor Q2 at one end thereof, and is connected to acollector terminal of the bipolar transistor Q1 at the other endthereof. The resistance R2 is connected to the resistance R1 at one endthereof, and is connected to a collector terminal of the bipolartransistor Q2 at the other end thereof. The resistance R5 is providedbetween the emitter terminals at which the bipolar transistors Q1 and Q2are connected in common and a ground node. The resistance R3 is providedbetween the base terminal of the bipolar transistor Q2 and the groundnode. The differential amplifier A1 receives, as inputs, respectiveelectric potentials on the collector sides of the bipolar transistors Q1and Q2, respectively. The MOS transistors MP1 and MP2 respectivelyreceive, as an input, an output voltage of the differential amplifier A1at their gate terminals, and are connected to a power supply node Vcc attheir source terminals. As a drain terminal of the MOS transistor MP1 isconnected to a connection node of the resistances R1 and R2, a feedbackloop is formed. Further, as a drain terminal of the MOS transistor MP2is connected to the resistance R4, a current I is supplied to theresistance R4. A detailed operational principle of the BGR core circuit10 will be described later.

The correcting circuit 20 shown in FIG. 2 includes an amplifier A2 thatreceives, as an input, the output voltage V_(BGR) of the BGR corecircuit 10 and forms a voltage follower; a bipolar transistor Q3 ofwhich a base terminal is connected to an output terminal of theamplifier A2; a resistance R6 that is provided between an emitterterminal of the bipolar transistor Q3 and the ground node; and P-channelMOS transistors MP3 and MP4 that forma current mirror circuit thatoutputs a correcting current I_(COMP) according to a current that flowson a collector side of the bipolar transistor Q3. Although there is noparticular limitation, the correcting current I_(COMP) is fed back tothe resistance R5. With such a feedback method, high accuracy is notnecessary in an element circuit such as an amplifier or a current mirrorused for the correcting circuit, and thus, it is possible to improve theaccuracy without large area or additional current. The amplifier A2 isprovided to supply a base current of the bipolar transistor Q3, and maynot be provided in a case where the influence on the output voltageV_(BGR) due to direct supply of the base current from the MOS transistorMP2 is negligible. A detailed operational principle of the correctingcircuit 20 will be described later.

Hereinafter, an operational principle of the reference voltagegenerating circuit 1 will be described in detail with reference to theBGR core circuit 10 and the correcting circuit 20.

(1) BGR Core Circuit 10

For ease of understanding about the BGR core circuit 10, a detaileddescription will be made using FIG. 3 that illustrates only the BGR corecircuit 10.

FIG. 3 is a circuit diagram illustrating an example of the BGR corecircuit 10 in the reference voltage generating circuit 1. In FIG. 3, acase where an offset of an amplifier is inserted in a positive sideinput of the amplifier A1 as an input offset voltage V_(OS) and to beequivalently represented is shown as an example.

In FIG. 3, it is assumed that a current that flows through theresistance R1 is I₁, a current that flows through the resistance R2 isI₂, a current that flows through MP1 and MP2 is I, a voltage at ajunction point of the resistance R1 and the resistance R2 is V3, andR₁=R₂=R₁₂. Further, in the following description, it is assumed that themirror ratio of the current mirror circuit or the like is 1:1, but themirror ratio may be changed without particular limitation.

For ease of understanding, in the following description, the basecurrent of the bipolar transistor is neglected for calculation, but in asimulation or the like in actual design, the calculation is performed inconsideration of the base current.

When a saturation current density of the bipolar transistor is Js, aunit area is A, a thermal voltage VT=kt/q, k is a Boltzmann constant, Tis the absolute temperature, and q is an elementary charge, Formula 1 isestablished with respect to a base-emitter voltage VBE1 of Q1 and abase-emitter voltage VBE2 of Q2.

$\begin{matrix}( {{Formula}\mspace{14mu} 1} ) & \; \\{{Formula}\mspace{14mu} 1} & \; \\{{V_{{BE}\; 1} = {V_{T}{\ln ( \frac{I_{1}}{{nJ}_{s}A} )}}},{V_{{BE}\; 2} = {V_{T}{\ln ( \frac{I_{2}}{J_{s}A} )}}}} & ( {{Formula}\mspace{14mu} 1} )\end{matrix}$

If the feedback by the amplifier A1 is normally operated, Formula 2 isestablished.

(Formula 2)

Formula 2

R ₁₂ I ₂ +V _(BE1) =V _(BE2)  (Formula 2)

If Formula 1 is substituted in Formula 2, Formula 3 is established.

$\begin{matrix}{\mspace{79mu} ( {{Formula}\mspace{14mu} 3} )} & \; \\{\mspace{79mu} {{Formula}\mspace{14mu} 3}} & \; \\{I_{2} = {\frac{V_{{BE}\; 2} - V_{{BE}\; 1}}{R_{12}} = {\frac{{V_{T}{\ln ( \frac{I_{2}}{J_{s}A} )}} - {V_{T}{\ln ( \frac{I_{1}}{{nJ}_{s}A} )}}}{R_{12}} = \frac{V_{T}{\ln ( {\frac{I_{2}}{I_{1}}n} )}}{R_{12}}}}} & ( {{Formula}\mspace{14mu} 3} )\end{matrix}$

Further, Formula 4 is established from the Kirchhoff's voltage law fromthe node of the electric potential V3 to the input of the amplifier A1.If Formula 4 is simplified, Formula 5 is established as the relationshipbetween the currents I₁ and I₂. If the current I₂ is deleted fromFormula 3 and Formula 5, Formula 6 that is an approximate formula may beestablished. Here, it is assumed that V_(OS)/I₁·R₁₂<<1.

$\begin{matrix}{\mspace{79mu} ( {{Formula}\mspace{14mu} 4} )} & \; \\{\mspace{79mu} {{Formula}\mspace{14mu} 4}} & \; \\{\mspace{76mu} {{V_{3} - {R_{12}I_{1}} + V_{OS}} = {V_{3} - {R_{12}I_{2}}}}} & ( {{Formula}\mspace{14mu} 4} ) \\{\mspace{76mu} ( {{Formula}\mspace{14mu} 5} )} & \; \\{\mspace{79mu} {{Formula}\mspace{14mu} 5}} & \; \\{\mspace{79mu} {I_{2} = {I_{1} - \frac{V_{OS}}{R_{12}}}}} & ( {{Formula}\mspace{14mu} 5} ) \\{\mspace{79mu} ( {{Formula}\mspace{14mu} 6} )} & \; \\{\mspace{79mu} {{Formula}\mspace{14mu} 6}} & \; \\{{I_{1} - \frac{V_{OS}}{R_{12}}} = {\frac{V_{T}{\ln ( {\frac{I_{2}}{I_{1}}n} )}}{R_{12}} = {\frac{V_{T}{\ln ( {\frac{I_{1} - \frac{V_{OS}}{R_{12}}}{I_{1}}n} )}}{R_{12}} = {{ \frac{V_{T}\ln \{ {( {1 - \frac{V_{OS}}{I_{1}R_{12}}} )n} \}}{R_{12}} \sim\frac{V_{T}}{R_{12}}}\{ {{\ln (n)} - \frac{V_{OS}}{I_{1}R_{12}}} \}}}}} & ( {{Formula}\mspace{14mu} 6} )\end{matrix}$

Here, if a quadratic equation with respect to I₁ in Formula 6 is solved,I₁ is expressed as Formula 7A. Here, D is expressed as Formula 7B.

$\begin{matrix}( {{Formula}\mspace{14mu} 7} ) & \; \\{{Formula}\mspace{14mu} 7} & \; \\{I_{1} = \frac{\sqrt{D} + {V_{T}{\ln (n)}} + V_{OS}}{2R_{12}}} & ( {{Formula}\mspace{14mu} 7A} ) \\{D = {( {V_{T}{\ln (n)}} )^{2} + {\{ {{2{\ln (n)}} - 4} \} V_{OS}V_{T}} + V_{OS}^{2}}} & ( {{Formula}\mspace{14mu} 7B} )\end{matrix}$

Accordingly, the output voltage V_(BGR) may be expressed as Formula 8.Further, as obvious from Formula 8, by setting the resistance ratio tobe R4<R3, the output voltage V_(BGR) may be a low output voltage (about1.0 V or less).

$\begin{matrix}( {{Formula}\mspace{14mu} 8} ) & \; \\{{Formula}\mspace{14mu} 8} & \; \\\begin{matrix}{V_{BGR} = {R_{4}I}} \\{= {R_{4}( {\frac{V_{{BE}\; 2}}{R_{3}} + I_{1} + I_{2}} )}} \\{= {R_{4}( {\frac{V_{{BE}\; 2}}{R_{3}} + {2I_{1}} - \frac{V_{OS}}{R_{12}}} )}} \\{= {R_{4}( {\frac{V_{{BE}\; 2}}{R_{3}} + {2I_{1}} - \frac{V_{OS}}{R_{12}}} )}} \\{= {R_{4}( {\frac{V_{{BE}\; 2}}{R_{3}} + {2\frac{\sqrt{D} + {V_{T}{\ln (n)}} + V_{OS}}{2R_{12}}} - \frac{V_{OS}}{R_{12}}} )}}\end{matrix} & ( {{Formula}\mspace{14mu} 8} )\end{matrix}$

If ΔV_(BGR) that indicates an error from V_(OS)=0 of the output voltageV_(BGR) is calculated on the basis of Formula 8, Formula 9 is obtained.

$\begin{matrix}( {{Formula}\mspace{14mu} 9} ) & \; \\{{Formula}\mspace{14mu} 9} & \; \\\begin{matrix}{{\Delta \; V_{BGR}} \equiv {R_{4}\{ {\frac{\Delta \; V_{{BE}\; 2}}{R_{3}} + {R_{1}( {{2\Delta \; I_{1}} - \frac{V_{OS}}{R}} )}} \}}} \\{= {R_{4}\{ {{\frac{V_{T}}{R_{3}}{\ln ( \frac{I_{2}}{I_{2}( {V_{OS} = 0} )} )}} +} }} \\ ( {{2\frac{\sqrt{D} - {V_{T}{\ln (n)}} + V_{OS}}{2R_{12}}} - \frac{V_{OS}}{R_{12}}} ) \} \\{= {R_{4}\{ {{\frac{V_{T}}{R_{3}}{\ln ( \frac{I_{2}}{I_{2}( {V_{OS} = 0} )} )}} + ( \frac{\sqrt{D} - {V_{T}{\ln (n)}}}{R_{12}} )} \}}}\end{matrix} & ( {{Formula}\mspace{14mu} 9} )\end{matrix}$

In Formula 9, for example, when R₃=315 kΩ, R₄=160 kΩ, R₁₂=66 kΩ, n=8 andVT=26 mV (in a case where the temperature is 27° C.), ΔV_(BGR) in thecase of V_(OS)=10 mV is about 2.54 mV.

Here, in order to compare operations and effects of the BGR core circuit10 according the present embodiment with a BGR circuit in the relatedart, an operational principle of the related art BGR circuit will bedescribed with reference to FIGS. 4 and 5.

FIG. 4 is a circuit diagram illustrating an example of an analysis BGRcore circuit reviewed on the basis of NPL 1.

In FIG. 4, a case where an offset voltage V_(OS) is inserted in apositive side input of an amplifier A is shown as an example. In FIG. 4,it is assumed that the emitter area ratio of bipolar transistors Q1 andQ2 is 1:n, currents are I₁ and I₂, a saturation current density of thebipolar transistor is Js, a unit area is A, and R₁=R_(z)=R₁₂.

In FIG. 4, Formula 10 is established with respect to a base-emittervoltage VBE1 of Q1 and a base-emitter voltage VBE2 of Q2.

$\begin{matrix}( {{Formula}\mspace{14mu} 10} ) & \; \\{{Formula}\mspace{14mu} 10} & \; \\{{V_{{BE}\; 1} = {V_{T}{\ln ( \frac{I_{1}}{J_{s}A} )}}},{V_{{BE}\; 2} = {V_{T}{\ln ( \frac{I_{2}}{{nJ}_{s}A} )}}}} & ( {{Formula}\mspace{14mu} 10} )\end{matrix}$

If the feedback by the amplifier is normally operated,

Formula 11 is established.

(Formula 11)

Formula 11

V _(BG1) +V _(OS) =V _(BE2) +R ₀ I ₂  (Formula 11)

If Formula 10 is substituted in Formula 11, Formula 12A is established.That is, Formula 12B is established.

$\begin{matrix}( {{Formula}\mspace{14mu} 12} ) & \; \\{{Formula}\mspace{14mu} 12} & \; \\{{{V_{T}{\ln ( \frac{I_{1}}{J_{s}A} )}} + V_{OS}} = {{V_{T}{\ln ( \frac{I_{2}}{{nJ}_{s}A} )}} + {R_{0}I_{2}}}} & ( {{Formula}\mspace{14mu} 12A} ) \\{I_{2} = \frac{{V_{T}{\ln ( {\frac{I_{1}}{I_{2}}n} )}} + V_{OS}}{R_{0}}} & ( {{Formula}\mspace{14mu} 12B} )\end{matrix}$

Further, Formula 13 is established from the Kirchhoff's voltage law froma power supply voltage V_(BGR) to the input of the amplifier A, andFormula 14 is established from the relationship between the currents I₁and I₂. Thus, Formula 15 that is an approximate formula may be obtained.Here, it is assumed that V_(OS)/I₁·R₁₂<<1.

$\begin{matrix}{\mspace{79mu} ( {{Formula}\mspace{14mu} 13} )} & \; \\{\mspace{79mu} {{Formula}\mspace{14mu} 13}} & \; \\{\mspace{79mu} {{V_{BGR} - {R_{12}I_{1}} + V_{OS}} = {V_{BGR} - {R_{12}I_{2}}}}} & ( {{Formula}\mspace{14mu} 13} ) \\{\mspace{79mu} ( {{Formula}\mspace{14mu} 14} )} & \; \\{\mspace{79mu} {{Formula}\mspace{14mu} 14}} & \; \\{\mspace{79mu} {I_{1} = {I_{2} + \frac{V_{OS}}{R_{12}}}}} & ( {{Formula}\mspace{14mu} 14} ) \\{\mspace{79mu} ( {{Formula}\mspace{14mu} 15} )} & \; \\{\mspace{79mu} {{Formula}\mspace{14mu} 15}} & \; \\{I_{2} = { \frac{{V_{T}{\ln( {\frac{I_{2} + \frac{V_{OS}}{R_{12}}}{I_{2}}n} )}} + V_{OS}}{R_{0}} \sim\frac{{V_{T}\{ {{\ln (n)} + \frac{V_{OS}}{I_{2}R_{12}}} \}} + V_{OS}}{R_{0}}}} & ( {{Formula}\mspace{14mu} 15} )\end{matrix}$

Here, since the Formula 15 may be changed into a simple quadraticequation, if a quadratic equation with respect to I₂ is solved, I₂ isexpressed as Formula 16A. Here, D is expressed as Formula 16B.

$\begin{matrix}{\mspace{79mu} ( {{Formula}\mspace{14mu} 16} )} & \; \\{\mspace{79mu} {{Formula}\mspace{14mu} 16}} & \; \\{\mspace{76mu} {I_{2} = \frac{\sqrt{D} + {V_{T}{\ln (n)}R_{12}} + {V_{OS}R_{12}}}{2R_{0}R_{12}}}} & ( {{Formula}\mspace{14mu} 16A} ) \\{D = {( {V_{T}{\ln (n)}R_{12}} )^{2} + {( {{4R_{12}R_{0}} + {2{\ln (n)}R_{12}^{2}}} )V_{OS}V_{T}} + {R_{12}^{2}V_{OS}^{2}}}} & ( {{Formula}\mspace{14mu} 16B} )\end{matrix}$

Accordingly, the output voltage V_(BGR) may be expressed as Formula 17.

$\begin{matrix}{\mspace{79mu} ( {{Formula}\mspace{14mu} 17} )} & \; \\{\mspace{79mu} {{Formula}\mspace{14mu} 17}} & \; \\\begin{matrix}{V_{BGR} = {V_{{BE}\; 1} + {R_{12}I_{1}}}} \\{= {V_{{BE}\; 1} + {R_{12}I_{1}}}} \\{= {V_{{BE}\; 1} + {R_{12}( {\frac{\sqrt{D} + {V_{T}{\ln (n)}R_{12}} + {V_{OS}R_{12}}}{2R_{0}R_{12}} + \frac{V_{OS}}{R_{12}}} )}}}\end{matrix} & ( {{Formula}\mspace{14mu} 17} )\end{matrix}$

As shown in Formula 17, the output voltage V_(BGR) has a configurationin which a linear coefficient that is proportional to the temperature iscanceled by adding a second term and thereafter to VBE. Accordingly, theoutput voltage V_(BGR) is about 1.2 V, and thus, it can be understoodthat the BGR circuit disclosed in NPL 1 is not suitable for a low powersupply voltage operation and a low output voltage in which a powersupply voltage is 1 V or lower, for example. Further, in Formula 8 andFormula 17, when comparing the second terms that indicate the current I₁(I₂) according to the voltage difference between the base-emittervoltages VBE of the bipolar transistors Q1 and Q2, while the offsetvoltage V_(OS) is handled in a direction of addition in the BGR corecircuit in FIG. 4, the offset voltage V_(OS) is handled in a directionof subtraction in the BGR core circuit 10 according to the presentembodiment. That is, it is understood that in the BGR core circuit 10according to the present embodiment, the influence of the offset voltageV_(OS) on the output voltage V_(BGR) is small. Specifically, if ΔV_(BGR)that indicates an error from V_(OS)=0 of the output voltage V_(BGR) ofthe BGR core circuit in FIG. 4 is calculated, Formula 18 is obtained.

$\begin{matrix}( {{Formula}\mspace{14mu} 18} ) & \; \\{{Formula}\mspace{14mu} 18} & \; \\\begin{matrix}{{\Delta \; V_{BGR}} \equiv {{\Delta \; V_{{BE}\; 1}} + {R_{12}\Delta \; I_{1}}}} \\{= {{V_{T}{\ln ( \frac{I_{1}}{I_{1}( {V_{OS} = 0} )} )}} +}} \\{{R_{12}( {\frac{\sqrt{D} + {V_{T}{\ln (n)}R_{12}} + {V_{OS}R_{12}}}{2R_{0}R_{12}} + \frac{V_{OS}}{R_{12}}} )}}\end{matrix} & ( {{Formula}\mspace{14mu} 18} )\end{matrix}$

In Formula 18, for example, when R₁₂=827.45 kΩ, R₀=100 kΩ, n=8 and VT=26mV (in a case where the temperature is 27° C.), ΔV_(BGR) in the case ofV_(OS)=10 mV is about 91.8 mV. It can be understood that the error ofthe output voltage V_(BGR) due to the offset voltage V_(OS) is largerthan that of the BGR core circuit 10 according to the presentembodiment.

FIG. 5 is a diagram illustrating an example of an analysis BGR corecircuit reviewed on the basis of PTL 1 as another example in the relatedart.

In FIG. 5, a case where an offset voltage V_(OS) is inserted in apositive side input of an amplifier A is shown as an example. In FIG. 5,assuming that a current that flows through a collector side of a bipolartransistor Q1 is I₁, a current that flows through a collector side of abipolar transistor Q2 is I₂, a saturation current density of the bipolartransistor is Js, and a unit area is A, and R2=R3=R, Formula 19 isestablished with respect to a base-emitter voltage VBE1 of Q1 and abase-emitter voltage VBE2 of Q2.

$\begin{matrix}( {{Formula}\mspace{14mu} 19} ) & \; \\{{Formula}\mspace{14mu} 19} & \; \\{{V_{{BE}\; 1} = {V_{T}{\ln ( \frac{I_{1}}{{nJ}_{s}A} )}}},{V_{{BE}\; 2} = {V_{T}{\ln ( \frac{I_{2}}{J_{s}A} )}}}} & ( {{Formula}\mspace{14mu} 19} )\end{matrix}$

If the feedback by the amplifier is normally operated, Formula 20 isestablished.

(Formula 20)

Formula 20

R ₀ I ₁ +V _(BE1) =V _(BE2)  (Formula 20)

Further, Formula 21 is established from the Kirchhoff's voltage law froma power supply Vcc to the input of the amplifier A, and Formula 22 isestablished from the relationship between the currents I₁ and I₂. Thus,Formula 23 that is an approximate formula may be established. Here, itis assumed that V_(OS)/I₁·R<<1.

$\begin{matrix}( {{Formula}\mspace{14mu} 21} ) & \; \\{{Formula}\mspace{14mu} 21} & \; \\{{V_{CC} - {RI}_{1}} = {V_{CC} - {RI}_{2} + V_{OS}}} & ( {{Formula}\mspace{14mu} 21} ) \\( {{Formula}\mspace{14mu} 22} ) & \; \\{{Formula}\mspace{14mu} 22} & \; \\{I_{2} = {I_{1} + \frac{V_{OS}}{R}}} & ( {{Formula}\mspace{14mu} 22} ) \\( {{Formula}\mspace{14mu} 23} ) & \; \\{{Formula}\mspace{14mu} 23} & \; \\\begin{matrix}{I_{1} = \frac{V_{{BE}\; 2} - V_{{BE}\; 1}}{R_{0}}} \\{= \frac{V_{T}{\ln ( {\frac{I_{2}}{I_{1}}n} )}}{R_{0}}} \\{= {{ \frac{V_{T}{\ln( {\frac{I_{1} + \frac{V_{OS}}{R}}{I_{1}}n} )}}{R_{0}} \sim\frac{V_{T}}{R_{0}}}\{ {{\ln (n)} + \frac{V_{OS}}{I_{1}R}} \}}}\end{matrix} & ( {{Formula}\mspace{14mu} 23} )\end{matrix}$

Here, similarly, if a quadratic equation with respect to I₁ is solved,I₁ is expressed as Formula 24A. Here, D is expressed as Formula 24B.

$\begin{matrix}( {{Formula}\mspace{14mu} 24} ) & \; \\{{Formula}\mspace{14mu} 24} & \; \\{I_{1} = \frac{\sqrt{D} + {V_{T}{\ln (n)}R}}{2R_{0}R}} & ( {{Formula}\mspace{14mu} 24A} ) \\{D = {( {V_{T}{\ln (n)}R} )^{2} + {4{RR}_{0}V_{OS}V_{T}}}} & ( {{Formula}\mspace{14mu} 24B} )\end{matrix}$

Accordingly, the output voltage V_(BGR) may be expressed as Formula 25.

$\begin{matrix}( {{Formula}\mspace{14mu} 25} ) & \; \\{{Formula}\mspace{14mu} 25} & \; \\\begin{matrix}{V_{BGR} = {V_{{BE}\; 2} + {R_{1}( {I_{1} + I_{2}} )}}} \\{= {V_{{BE}\; 2} + {R_{1}( {{2I_{1}} + \frac{V_{OS}}{R}} )}}} \\{= {V_{{BE}\; 2} + {R_{1}( {{2\frac{\sqrt{D} + {V_{T}{\ln (n)}R}}{2R_{0}R}} + \frac{V_{OS}}{R}} )}}}\end{matrix} & ( {{Formula}\mspace{14mu} 25} )\end{matrix}$

As shown in Formula 25, the output voltage V_(BGR) has a configurationin which a linear coefficient that is proportional to the temperature iscanceled by adding a second term and thereafter to VBE. Accordingly, ina similar way to the BGR circuit in FIG. 4, the output voltage V_(BGR)is about 1.2 V, and thus, it can be understood that the BGR circuitdisclosed in PTL 1 is not suitable for a low power supply voltageoperation and a low output voltage in which a power supply voltage is 1V or lower, for example.

Here, if ΔV_(BGR) that indicates an error from V_(OS)=0 of the outputvoltage V_(BGR) is calculated, Formula 26 is obtained.

$\begin{matrix}( {{Formula}\mspace{14mu} 26} ) & \; \\{{Formula}\mspace{14mu} 26} & \; \\\begin{matrix}{{\Delta \; V_{BGR}} \equiv {{\Delta \; V_{{BE}\; 2}} + {R_{1}( {{2\Delta \; I_{1}} + \frac{V_{OS}}{R}} )}}} \\{= {{V_{T}{\ln ( \frac{I_{2}}{I_{2}( {V_{OS} = 0} )} )}} + ( \frac{\sqrt{D} - {V_{T}{\ln (n)}R}}{2R_{0}R} )}}\end{matrix} & ( {{Formula}\mspace{14mu} 26} )\end{matrix}$

In Formula 26, for example, when R=540 kΩ, R₀=38 kΩ, n=8 and VT=26 mV(in a case where the temperature is 27° C.), ΔV_(BGR) in the case ofV_(OS)=10 mV is 7.01 mV, in which the error of the output voltageV_(BGR) is 1/10 or less compared with that of the BGR core circuit inFIG. 4.

FIG. 6 is a diagram quantitatively illustrating input offset voltagedependence of the output voltage V_(BGR) in each BGR core circuit.

Characteristic lines of respective BGR core circuits in FIG. 6 representrespective characteristics of ΔV_(BGR) when the offset voltages V_(OS)in Formula 9, Formula 18 and Formula 26 are changed. The numerical valueexamples in the description of the above-mentioned BGR core circuits areapplied to constants of resistance values or the like in Formula 9,Formula 18 and Formula 26.

As shown in FIG. 6, it can be understood that the BGR core circuit 10according to the present embodiment has a low input offset voltagedependence compared with a topology of the circuit in FIG. 4.

FIG. 7 is an enlarged view of FIG. 6. In FIG. 7, characteristic lines ofthe BGR core circuit 10 and the BGR core circuit (FIG. 5) based on PTL 1are shown.

As shown in FIG. 7, it can be understood that the BGR core circuit 10according to the present embodiment has a low input offset voltagedependence compared with a topology of the circuit in FIG. 5. As obviousfrom Formula 9, it is possible to suppress the variation of the outputvoltage V_(BGR) compared with the BGR core circuit in FIG. 5 byselecting appropriate values as resistance values and an emitter arearatio n of the bipolar transistors.

FIG. 8 is a diagram illustrating simulation results of three BGR corecircuits. Element conditions in simulation are as follows. That is, agate length in a CMOS process is 90 nm, MOS transistors are used, andresistances and capacitances of a Typ model are used. In FIG. 8, when ajunction temperature Tj is 25° C., an output voltage V_(BGR) when thepower supply voltage Vcc is changed from 0 V to 5.5 V is shown.

As shown in FIG. 8, since the output voltages V_(BGR) of the BGR corecircuit in FIG. 4 and the BGR core circuit in FIG. 5 are about 1.2 V,the power supply voltage Vcc may be operated from about 2.0 V. This isalso easily understood from the fact that the output voltage V_(BGR) hasthe configuration in which the linear coefficient that is proportionalto the temperature is canceled by adding a PTAT voltage to VBE, as shownin Formula 17 and Formula 25.

On the other hand, in the BGR core circuit 10 according to the presentembodiment, as shown in FIG. 8, it can be understood that the outputvoltage V_(BGR) is 1.0 V or lower and the power supply voltage Vcc maybe operated from about 1.0 V. This is easily understood from Formula 8.That is, since the BGR core circuit 10 according to the presentembodiment has the configuration in which the coefficient that isproportional to the temperature is canceled by adding the current thatflows through the resistance R3, based on VBE of the bipolar transistorQ2, and a PTAT current that is proportional to the absolute temperatureand the added current is converted into a voltage by the resistance R4to be output, it is possible to obtain a low voltage output by adjustingthe ratio of the resistance R3 and the resistance R4.

As described above, according to the BGR core circuit 10 according tothe present embodiment, it is possible to reduce the influence of offsetof the amplifier A1 on the output voltage V_(BGR). Further, since thelow output voltage V_(BGR) may be generated by adjusting the ratio ofthe resistance R3 and the resistance R4, the BGR core circuit 10 may beoperated at a lower power supply voltage Vcc. Further, as shown in FIGS.2 and 3, as the resistance R5 is inserted between the emitter terminalof the bipolar transistors Q1 and Q2 and the ground node, it is possibleto shift a common input voltage of the amplifier A1 to be high, whichmakes it possible to achieve an easy design.

(2) Correcting Circuit 20

A principle of the temperature correction in the correcting circuit 20will be described.

First, the temperature dependence of a base-emitter voltage V_(BE) of abipolar transistor will be described. The temperature dependence of thebase-emitter voltage is expressed as Formula 28 when the temperaturedependence of a collector current IC is expressed as Formula 27 as shownin the above-mentioned NPL 2.

$\begin{matrix}{\mspace{79mu} ( {{Formula}\mspace{14mu} 27} )} & \; \\{\mspace{79mu} {{Formula}\mspace{14mu} 27}} & \; \\{\mspace{79mu} {I_{C} \propto T^{m}}} & ( {{Formula}\mspace{14mu} 27} ) \\{\mspace{79mu} ( {{Formula}\mspace{14mu} 28} )} & \; \\{\mspace{79mu} {{Formula}\mspace{14mu} 28}} & \; \\{{V_{BE}(T)} = {{V_{G\; 0}( {1 - \frac{T}{T_{R}}} )} + {\frac{T}{T_{R}}{V_{BE}( T_{R} )}} - {( {\eta - m} )\frac{kT}{q}{\ln ( \frac{T}{T_{R}} )}}}} & ( {{Formula}\mspace{14mu} 28} )\end{matrix}$

Here, T_(R) represents a reference temperature. Further, η is a constantdepending on a device structure of a bipolar transistor, and has a valueof about 3.6 to 4.0. V_(G0) is an extrapolation value of a band gapvoltage to the absolute temperature 0 K. As described above, m is “1” ina case where the collector current Ic is proportional to the absolutetemperature. Formula 28 is changed into Formula 29.

$\begin{matrix}{\mspace{79mu} ( {{Formula}\mspace{14mu} 29} )} & \; \\{\mspace{79mu} {{Formula}\mspace{14mu} 29}} & \; \\{{V_{BE}(T)} = {\{ {V_{G\; 0} + {( {\eta - m} )\frac{{KT}_{R}}{q}}} \} - {\frac{V_{G\; 0} + {( {\eta - m} )\frac{{kT}_{R}}{q}} - {V_{BE}( T_{R} )}}{T_{R}}T} + {( {\eta - m} )\frac{k}{q}\{ {T - T_{R} - {T\; {\ln ( \frac{T}{T_{R}} )}}} \}}}} & ( {{Formula}\mspace{14mu} 29} )\end{matrix}$

In Formula 29, the first term is a constant that does not depend on thetemperature, and the second term is a term that is proportional to theabsolute temperature. Further, the third term is a term that is notproportional to the absolute temperature and shows non-lineardependence. That is, the base-emitter voltage VBE shows non-lineardependence on the temperature.

FIG. 9 is a diagram illustrating the non-linear dependence of thebase-emitter voltage VBE on the temperature.

As shown in FIG. 9, a characteristic of the third term in Formula 29 isa non-linear characteristic. A straight line indicated by referencenumeral 300 is shown for comparison, which is an example of acharacteristic that is proportional to the temperature.

A general formula (for example, Formula 8, Formula 17, and Formula 25)of the BGR circuit shown in (1) the BGR core circuit 10 described abovemay be expressed as Formula 30A or Formula 30B when constants determinedby the resistance ratio are K and L. Here, ΔV_(BE) is a voltagedifference of base-emitter voltages VBE of two bipolar transistors Q1and Q2.

     (Formula  30)      Formula  30 $\begin{matrix}{V_{BGR} = {{V_{BE} + {{K\Delta}\; V_{BE}}} = {{V_{BE} + {K^{\prime}V_{T}}} = {V_{BE} + {K^{\prime}\frac{kT}{q}}}}}} & ( {{Formula}\mspace{14mu} 30A} ) \\{V_{BGR} = {{{LV}_{BE} + {{K\Delta}\; V_{BE}}} = {{{LV}_{BE} + {K^{\prime}V_{T}}} = {{{LV}_{BE} + {K^{\prime}\frac{kT}{q}}} < {1.2\mspace{14mu} V}}}}} & ( {{Formula}\mspace{14mu} 30B} )\end{matrix}$

As understood from Formula 30A and Formula 30B, since the temperaturedependence of the base-emitter voltage VBE of the first term shows thenon-linearity, it can be understood that it is logically impossible tocorrect the non-linear temperature dependence by only the second termthat is proportional to the absolute temperature. Thus, in the referencevoltage generating circuit 1 according to the present embodiment,correction of the non-linear temperature dependence of the outputvoltage V_(BGR) is performed by the following method.

In FIG. 2, an electric potential at the junction point of the resistanceR5 and the emitter terminal of the bipolar transistors Q1 and Q2 is setto V2, and the correcting current is set to I_(COMP). Further, for easeof understanding, it is assumed that R₁=R₂=R₁₂, and I₁=I₂=I_(PTAT).Here, I_(PTAT) may be expressed as Formula 31 byV_(BE2)=V_(BE1)+R₁₂·I_(PTAT).

(Formula  31) $\begin{matrix}{{Formula}\mspace{14mu} 31} & \; \\{I_{PTAT} = {\frac{V_{{BE}\; 2} - V_{{BE}\; 1}}{R_{12}} = {{\frac{\Delta \; V_{BE}}{R_{12}} + {V_{T}\frac{\ln (n)}{R_{12}}}} \propto T}}} & ( {{Formula}\mspace{14mu} 31} )\end{matrix}$

Next, since a current I is expressed as Formula 32 from the Kirchhoff'scurrent law and a current I_(R3) that flows through the resistance R3 isexpressed as Formula 33, the current I is expressed as Formula 34.

$\begin{matrix}( {{Formula}\mspace{14mu} 32} ) & \; \\{{Formula}\mspace{14mu} 32} & \; \\{I = {{2I_{PTAT}} + I_{R\; 3}}} & ( {{Formula}\mspace{14mu} 32} ) \\( {{Formula}\mspace{14mu} 33} ) & \; \\{{Formula}\mspace{14mu} 33} & \; \\{I_{R\; 3} = {\frac{V_{{BE}\; 2} - V_{2}}{R_{3}} = \frac{V_{{BE}\; 2} + {( {2_{PTAT} + I_{COMP}} )R_{5}}}{R_{3}}}} & ( {{Formula}\mspace{14mu} 33} ) \\( {{Formula}\mspace{14mu} 34} ) & \; \\{{Formula}\mspace{14mu} 34} & \; \\{I = {{2I_{PTAT}} + \frac{V_{{BE}\; 2} + {( {2_{PTAT} + I_{COMP}} )R_{5}}}{R_{3}}}} & ( {{Formula}\mspace{14mu} 34} )\end{matrix}$

Accordingly, the output voltage V_(BGR) is expressed as Formula 35.

     (Formula  35) $\begin{matrix}{\mspace{79mu} {{Formula}\mspace{14mu} 35}} & \; \\\begin{matrix}{V_{BGR} = {{R_{4}I} = {R_{4}\{ {{2I_{PTAT}} + \frac{V_{{BE}\; 2} + {( {{2I_{PTAT}} + I_{COMP}} )R_{5}}}{R_{3}}} \}}}} \\{= {R_{4}\{ {{2I_{PTAT}} + \frac{V_{{BE}\; 2} + {( {{2I_{PTAT}} + I_{COMP}} )R_{5}}}{R_{3}}} \}}} \\{= {R_{4}\{ {\frac{V_{{BE}\; 2}}{R_{3}} + {( {2 + \frac{2R_{5}}{R_{3}}} )I_{PTAT}} + \frac{I_{COMP}R_{4}}{R_{3}}} \}}}\end{matrix} & ( {{Formula}\mspace{14mu} 35} )\end{matrix}$

It is possible to lower the output voltage V_(BGR) by adjusting theresistance R3 and the resistance R4 in a similarly way to theabove-described BGR core circuit 10 in FIG. 3.

Further, the correcting current I_(COMP) may be expressed as Formula 36by setting the mirror ratio of MP3 and MP4 to 1:1.

(Formula  36) $\begin{matrix}{{Formula}\mspace{14mu} 36} & \; \\{I_{COMP} = \frac{V_{BGR} - V_{{BE}\; 3}}{R_{6}}} & ( {{Formula}\mspace{14mu} 36} )\end{matrix}$

As shown in Formula 36, the correcting current I_(COMP) is generated onthe basis of a voltage difference of the output voltage V_(BGR) and abase-emitter voltage VBE3 of the bipolar transistor Q3. SinceV_(BGR)≦V_(BE3) on low temperature side, the correcting current I_(COMP)does not flow, and on high temperature side, the correcting currentI_(COMP) is added from the temperature at which V_(BGR)=V_(BE3). Thus,the correcting current I_(COMP) is expressed as Formula 37.

(Formula  37) $\begin{matrix}{{Formula}\mspace{14mu} 37} & \; \\{I_{COMP} = \{ \begin{matrix}{0( {V_{BGR} \leq V_{{BE}\; 3}} )} \\{\frac{V_{BGR} - V_{{BE}\; 3}}{R_{6}}( {V_{BGR} \geq V_{{BE}\; 3}} )}\end{matrix} } & ( {{Formula}\mspace{14mu} 37} )\end{matrix}$

Accordingly, in the reference voltage generating circuit 1, thenon-linearity of the base-emitter terminal VBE that is the first term inFormula 35 is linearly corrected by IPTAT that is the second term, andis non-linearly corrected by the correcting current I_(COMP) that is thethird term. Further, by generating the correcting current I_(COMP)according to a difference between two voltages (the output voltageV_(BGR) and the base-emitter voltage V_(BE3)) with the temperaturedependence, it is possible to add the correcting current I_(COMP) fromthe temperature at which V_(BGR)=V_(BE3). Further, it is possible tocontrol the inclination of the correcting current I_(COMP) by the valueof the resistance R6. Thus, if the characteristic of V_(BGR) is adjustedso that V_(BGR)=V_(BE3) in a desired temperature range where thetemperature characteristic is to be corrected, it is possible to correctthe non-linear temperature characteristic.

The above calculation is an approximate calculation. In actuality, aloop is formed between the BGR core circuit 10 and the correctingcircuit 20 to cause feedback, and thus, the values of the resistance,the correcting current I_(COMP) and the like show some variances fromthe above calculation. Precise values may be calculated by simulation.Further, in this example, since it is assumed that the power supplyvoltage Vcc is about 1.0 V and the output voltage V_(BGR) is set to beabout 0.63 V, the bipolar transistor Q3 of the correcting circuit 20 hasa single-stage configuration, but as described later, in a case wherethe output voltage is about 1.2 V, it is preferable that the bipolartransistor Q3 of the correcting circuit 20 have a double-stageconfiguration.

FIG. 10 is a diagram illustrating a principle of a method of correctinga non-linear temperature characteristic by the reference voltagegenerating circuit 1.

In FIG. 10, VBGR_PTAT shows an example of a waveform in a case whereonly correction using the voltage VPTAT that is proportional to theabsolute temperature is performed for the base-emitter voltage VBE whenthe correcting current I_(COMP) is neglected. Further, the voltageVBGR_PTAT has a bowl shape, and shows a case where a circuit constant ofa resistance value or the like is adjusted so that the temperature atwhich a temperature coefficient is zero is achieved on low temperatureside. Further, Vth shows an example of a voltage waveform correspondingto the third term in Formula 35. As shown in FIG. 10, in the referencevoltage generating circuit 1, by adding the voltage Vth that increaseson high temperature side from the temperature T1 at whichV_(BGR)=V_(BE3), it is possible to reduce the temperature dependence ofthe output voltage V_(BGR).

Here, in order to compare operations and effects of the non-linearcorrecting circuit 20 according to the present embodiment with the BGRcircuit in the related art, the temperature correction method in therelated art will be described.

FIG. 11 is a diagram illustrating a correction principle of a non-linearcharacteristic for a BGR circuit reviewed on the basis of PTL 1.

In FIG. 11, a resistance R1 is divided into two resistances R11 and R12,an electric potential of a node between R11 and R12 is represented asV₂, and respective currents of R11 and R12 are represented as I₁₁ andI_(R12).

An output voltage V_(BGR) in a case where a correcting current I_(COMP)is not added is expressed as Formula 38.

(Formula  38) $\begin{matrix}{{Formula}\mspace{14mu} 38} & \; \\{V_{BGR} = {V_{{BE}\; 1} + {2\frac{\Delta \; V_{BE}}{R_{0}}( {R_{11} + R_{12}} )}}} & ( {{Formula}\mspace{14mu} 38} )\end{matrix}$

In this circuit, the correcting current I_(COMP) that is notproportional to the absolute temperature is supplied to a node of anelectric potential V2 for correction of the non-linear characteristic.Here, it is assumed that a current I_(PTAT) ² that is proportional tothe square of the absolute temperature is set as the correcting currentI_(COMP). In this case, since Formula 39 is established according to theThevenin's theorem, as shown in FIG. 11, a circuit between a node of anelectric potential V1 and a ground node may be re-drawn as a serialconnection of a resistance Rth and a voltage source Vth.

(Formula 39)

Formula 39

R _(th) =R ₁₁ +R ₁₂ ,V _(th) =R ₁₂ I _(PTAT) ²  (Formula 39)

That is, the Thevenin's equivalent voltage VTH has a characteristic(non-linear characteristic) that increases on high temperature side.Accordingly, an output voltage V_(BGR) in a case where the correctingcurrent I_(COMP) (I_(PTAT) ²) is added is expressed as Formula 40.

(Formula  40) $\begin{matrix}{{Formula}\mspace{14mu} 40} & \; \\{V_{BGR} = {V_{{BE}\; 1} + {2\frac{\Delta \; V_{BE}}{R_{0}}( {R_{11} + R_{12}} )} + {I_{comp}R_{12}}}} & ( {{Formula}\mspace{14mu} 40} )\end{matrix}$

As shown in Formula 40, if a non-linear correction term (the third term)based on the current I_(PTAT) ² that is proportional to the square ofthe absolute temperature is added, it is understood that a temperaturecharacteristic of V_(BGR) is formed in a cubic curve and a temperaturedrift is reduced. As described above, in which a reference voltagesource should have a flat temperature characteristic in a predeterminedtemperature range (for example, −55° C. to 160° C.). Thus, in a casewhere the temperature correction is performed, it is preferable toperform correction in a necessary temperature range. However, forexample, in a case where the current I_(PTAT) ² is generated by theI_(PTAT) ² current generating circuit disclosed in NPL 3 to NPL 5, thecurrent becomes a current that is changed from the absolute temperature0 K. Thus, as shown in Formula 40, the output voltage V_(BGR) becomes avalue in which the non-linear correction term (I_(COMP)·R_(p12)) isadded from the absolute temperature 0 K. This is not suitable for a casewhere a temperature characteristic in a predetermined temperature rangeis to be improved. Actually, the present inventors reviewed in advanceand found that it is difficult to realize an appropriate temperaturecorrection in the correction method of adding I_(PTAT) ² using theI_(PTAT) ² current generating circuit. Further, in the I_(PTAT) ²current generating circuit, both of the size of the circuit and thenumber of elements are increased, which complicates a circuitconfiguration and is not suitable for a low voltage. On the other hand,according to the non-linear correcting circuit 20 according to thepresent embodiment, it is possible to generate the correcting currentI_(COMP) by a simple circuit configuration in which the number ofelements is small, and to generate the correcting current I_(COMP) to bechanged at a predetermined temperature or higher. Thus, it is possibleto easily perform non-linear correction of the output voltage V_(BGR) ina desired temperature range.

FIGS. 12A and 12B are diagrams illustrating an example of thetemperature dependence of a reference voltage generating circuitaccording to a simulation. In FIGS. 12A and 12B, simulation results ofrespective output voltages V_(BGR) of the reference voltage generatingcircuit 1, the BGR circuit (FIG. 4) based on NPL 1 and the BGR circuit(FIG. 5) based on PTL 1 are shown.

In FIG. 12A, characteristic waveforms of three circuits are shown, andin FIG. 12B, values of a temperature coefficient TC (ppm/° C.) and atemperature drift ΔV_(BGR) (mV) that is a voltage variation due to thetemperature change are shown. The temperature coefficient TC is definedas Formula 41A by the BOX method, and the temperature drift ΔV_(BGR)(mV) is defined as Formula 41B.

$\begin{matrix}{( {{Formula}\mspace{14mu} 41} )\;} & \; \\{{Formula}\mspace{14mu} 41} & \; \\\begin{matrix}{{TC} = {\frac{1}{V_{ave}}\frac{V_{BGRmax} - V_{BGRmin}}{T_{\max} - T_{\min}}}} & {( {{ppm}/C} )}\end{matrix} & ( {{Formula}\mspace{14mu} 41A} ) \\\begin{matrix}{{\Delta \; V_{BGR}} = ( {V_{BGRmax} - V_{BGRmin}} )} & {({mV})}\end{matrix} & ( {{Formula}\mspace{14mu} 41B} )\end{matrix}$

In the simulation, a device model is used in which elements such as aMOS transistor, a resistance and a capacitance, manufactured in astandardized manner by a CMOS process having a gate length of 90 nm, areassumed to be provided. The power supply voltage Vcc is set to 3.0 V forthe BGR circuit (FIG. 4) based on NPL 1 and the BGR circuit (FIG. 5)based on PTL 1 since it is difficult to achieve a low power supplyvoltage, and is set to 1.0 V for the reference voltage generatingcircuit 1. A temperature variable range is −40° C. to 125° C. Since theoutput voltage V_(BGR) of the reference voltage generating circuit 1 is1.0 V or lower (about 0.63 V), a characteristic line of the outputvoltage V_(BGR) of the reference voltage generating circuit 1 is movedin parallel upward on the vertical axis for comparison in FIG. 12A.

As shown in FIGS. 12A and 12B, since the BGR circuit (FIG. 4) based onNPL 1 and the BGR circuit (FIG. 5) based on PTL 1 are only linearlycorrected, the temperature drift ΔV_(BGR) (mV) is from about 2.6 mV toabout 3.2 mV, which is large, but in the reference voltage generatingcircuit 1, it can be understood that the temperature drift ΔV_(BGR) (mV)is about 0.25 mV that is suppressed into about 1/10.

Next, components or the like in the reference voltage generating circuit1 will be described in detail.

FIGS. 13A to 13D are diagrams illustrating an example of layouts ofbipolar transistors Q1 and Q2 in the BGR core circuit 10. Although thereis no particular limitation, in FIGS. 13A to 13D, a case where acollector is formed in a vertical direction using an n-type deep welldwel and the periphery of the bipolar transistors Q1 and Q2 issurrounded by the n-type deep well dwel is shown as an example. Further,although there is no particular limitation, except for FIG. 13C, a casewhere the emitter area ratio of the bipolar transistors Q1 and Q2 is 8:1is shown as an example.

In FIG. 13A, a case where the sizes of the n-type deep wells dwel thatform the collectors are formed to be the same in two bipolar transistorsQ1 and Q2 is shown. With such a configuration, by making the influenceof noise that propagate from a semiconductor substrate be uniform in Q1and Q2 by capacitance coupling, it is possible to cancel the noise ascommon mode noise.

In FIG. 13B, a case where eight bipolar transistors that include a dummyare arranged in a similar way to Q1 in a deep well dwel where thebipolar transistor Q2 having a small emitter area is formed, in additionto formation of the n-type deep well dwel shown in FIG. 13A, is shown.In this case, by providing interconnection for one among eighttransistors in the region where Q2 is formed, the size ratio of Q1 andQ2 is set to 8:1. Thus, in addition to the effect of FIG. 13A, it ispossible to reduce the influence of the dimensional variation information of the transistors.

In FIG. 13C, a case where nine bipolar transistors that include a dummyare arranged in each deep well dwel where the bipolar transistors Q1 andQ2 are formed, in addition to formation of the n-type deep well dwelshown in FIG. 13A, is shown. For example, in a case where one of Q1 andQ2 becomes the exponent of 2 so that the size ratio of Q1 and Q2 becomes9:1, if a transistor at the center of the transistors that are arrangedby the same number as that of Q1 is set to Q2, it is possible to furtherreduce the dimensional variation.

In FIG. 13D, a case where nine bipolar transistors that include a dummyare arranged in one deep well dwel, in addition to formation of then-type deep well dwel shown in FIG. 13A, is shown. In this case, if atransistor (B) that is at the center of the transistors in the region ofthe deep well dwel is set to Q2 and the other eight transistors (A) areset to Q1, it is possible to reduce the dimensional variation, and toform the transistors with a small area compared with FIG. 13C.

FIGS. 14A and 14B are circuit diagrams illustrating an example of anamplifier A1 in the reference voltage generating circuit 1.

FIG. 14A shows an example of the amplifier A1 that uses an N-channel MOStransistor as an input stage. The amplifier in FIG. 14A includes aninitial stage section and an output stage section. The initial stagesection includes two N-channel MOS transistors M1 and M2 that form adifferential input stage, a current source it that is provided between asource terminal and the ground node, and two P-channel MOS transistorsM3 and M4 that are provided between drain terminals of M1 and M2 and apower supply voltage Vcc and form an active load by a current mirrorcircuit. Further, the output stage section includes the P-channel MOStransistor M3 in which an initial stage output signal is input to thegate terminal and a source is connected to a node of the power supplyvoltage Vcc, and an inverting amplifier circuit that uses a currentsource i3 provided between a drain terminal of M3 and the ground node asa load. A capacitor Cf that is a phase compensating circuit and aresistance Rf are provided between a gate terminal and the drainterminal of M3.

FIG. 14B shows an example of the amplifier A1 that uses an N-channel MOStransistor as an input stage. The amplifier in FIG. 14B includes aninitial stage section, an output stage section and a current sourcesection. In a case where the reference voltage generating circuit 1 isformed, it is necessary to reduce power consumption, but a gain of theamplifier unnecessarily increases to cause a disadvantageous effect andphase compensation may become difficult. The amplifier shown in FIG. 14Bhas a circuit configuration for reduction in power consumption, andincludes an amplifying section at the initial stage section thatreceives a differential input by the N-channel MOS transistors, anoutput stage section that includes an inverting amplifying circuit thatincludes a P-channel MOS transistor and is connected to the ground atits source, and a current source section that drives these components.The current source section converts a voltage difference of gate-sourcevoltages of n-channel MOS transistors M12 and M13 for a stable supply ofa fine current into a current by a resistance Rref to generate aconverted current Iref. The current Iref determines bias currents i1 andi3 of the initial stage section and the output stage section in the MOStransistors M14 and M15 as the form of a current mirror. In a case wherea current value of the current i1 is set to be small, in order toprevent the gain of the amplifier in the initial stage from beingincreased and to prevent phase compensation from being difficult,current sources M6 and M7 in which a constant current i2 flows arerespectively connected in parallel with MOS transistors M4 and M5 thatform the current mirror that functions to determine the gain. As theconstant current Iref flows in the MOS transistors M13 and M11, and M9of diode connection and MOS transistors M6 to M9 have the form of thecurrent mirror, it is possible to form a constant current i3. Thus, itis easy to perform phase compensation. That is, pole-zero compensation(Rf and Cf are connected in series at the output stage) that is easy fordesigning may be performed, in addition to the mirror compensation usedin the related art.

In the above description of FIG. 2, a circuit configuration thatexcludes a start-up circuit for ease of understanding of the operationalprinciple of the reference voltage generating circuit 1 is shown, butthe reference voltage generating circuit 1 further includes the start-upcircuit.

FIG. 15 is a circuit diagram illustrating an example of the referencevoltage generating circuit 1 that includes a start-up circuit.

In the reference voltage generating circuit 1, the output voltageV_(BGR) may be stabilized at 0 V in start-up, for example, when a powersupply voltage is input. As a solution of this problem, a start-upcircuit 30 is provided in the reference voltage generating circuit 1 toforce a current to flow, to thereby start up the circuit.

Hereinafter, an operation of the start-up circuit 30 will be described.For example, when a gate electric potential V1 of a MOS transistor MP1is Vcc, MP1 is turned off, and thus, a current does not flow. Here,since a MOS transistor MP2 is turned off, the output voltage V_(BGR)becomes a ground electric potential, and a MOS transistor MN1 is turnedoff. An electric potential V4 of a node to which a drain terminal of theMOS transistor MN1 is connected becomes Vcc-|VTHP| when a thresholdvoltage of a MOS transistor MP7 is set to VTHP, and a MOS transistor MN2is turned on. Thus, the gate electric potential V1 of MP1 drops fromVcc, and the BGR core circuit 10 may be operated at a normal bias.

The output voltage V_(BGR) may be generated by the start-up circuit 30without error when power is input or sleep is released, for example.Further, even in a case where disturbance or the like occurs in a normaloperation, the output voltage V_(BGR) is returned without delay and isstably generated. Furthermore, according to the circuit configuration ofthe start-up circuit 30, since the gate electric potential V4 of the MOStransistor MN2 may be reduced to be equal to or lower than a thresholdvoltage VTHN of the MOS transistor MN2 by appropriately selectingtransistor sizes of the MOS transistors MP7, MN1 and MN2, it is possibleto neglect the current of the MOS transistor MN2, and not to give aninfluence on the operation of the BGR core circuit 10. The start-upcircuit 30 is an example, and a start-up circuit with a differentcircuit configuration may be provided in the reference voltagegenerating circuit 1.

FIG. 16 is a diagram illustrating a configuration example of a circuitin which an LPF (low pass filter) is inserted in a power supply (Vcc)line.

Since the BGR core circuit 10 and the correcting circuit 20 according tothe present embodiment have a small circuit size and achieve low powerconsumption, as shown in FIG. 16, a configuration in which a low passfilter 60 is inserted in the power source Vcc line and an output voltageVcc_LPF of the low pass filter 60 is supplied to the BGR core circuit10, the correcting circuit 20, a regulator circuit (reference currentsource) 70 and the like may be used. Thus, it is possible to reduce apower supply rejection ratio (PSRR), and to increase resistance againstpower supply voltage variation. The low pass filter 60 is realized by aresistance element and a capacitance element, for example, but adifferent circuit configuration may be used as long as a low passtransmission property is obtained.

Next, a system to which the reference voltage generating circuit 1 isapplied will be described.

FIGS. 17A to 17D are diagrams illustrating an example of the system towhich the reference voltage generating circuit 1 is applied.

FIG. 17A shows an application example to an AD converter. The ADconverter converts an analog input signal into a digital signal on thebasis of a V_(BGR) voltage generated by the reference voltage generatingcircuit 1 or a voltage generated on the basis of the V_(BGR) voltage,and outputs the result.

FIG. 17B shows an application example to a DA converter. The DAconverter converts a digital input signal into an analog signal on thebasis of a V_(BGR) voltage generated by the reference voltage generatingcircuit 1 or a voltage generated on the basis of the V_(BGR) voltage,outputs the result.

FIG. 17C shows an application example to a reference current source. Thereference current source generates a reference current IREF on the basisof a V_(BGR) voltage generated by the reference voltage generatingcircuit 1 or a voltage generated on the basis of the V_(BGR) voltage,and outputs the result.

FIG. 17D shows an application example to a temperature sensor. Thetemperature sensor measures the temperature on the basis of a VPTATvoltage that is proportional to the temperature and a V_(BGR) voltagewith low temperature dependence, and outputs the measurement result. Amethod of generating the VPTAT voltage will be described later.

FIG. 18 is a block diagram illustrating an example of a semiconductorintegrated circuit device to which the reference voltage generatingcircuit 1 is applied.

Although there is no particular limitation, the semiconductor integratedcircuit device 100 is a system LSI in which a power supply circuit isinstalled, for example.

The semiconductor integrated circuit device 100 includes a power supplycircuit 50, a CPU (central processing unit) 45, a register 46, anon-volatile storage element 47, a peripheral circuit 48, and an inputand output circuit 49, for example. The power supply circuit 50 includesthe reference voltage generating circuit 1, a reference voltage buffercircuit 42, a main regulator 43 that is a main power source, a subregulator 44 that is a standby power source, and a power supply controlsection 41, for example. These circuits are operated by receiving apower supply voltage VCC supplied from an external terminal, generate aninternal voltage Vint by decreasing VCC, and supply the result as anoperating voltage of the CPU 45, the register 46, the non-volatilestorage element 47 and the peripheral circuit 48 that form the systemLSI.

For example, in a case where the system LSI 100 is driven by a battery,a low power supply voltage and low power consumption are obtained.However, since each circuit is not able to secure a sufficient margindue to the low power supply voltage, a request for a high accuratecharacteristic is expected. Thus, by applying the reference voltagegenerating circuit 1 according to the present embodiment to the systemLSI, the low power supply voltage operation and the low output voltagemay be effectively realized. Further, for higher accuracy, it ispreferable that the reference voltage generating circuit 1 be formed bythe CMOS process. Particularly, since the influence of offset of thedifferential amplifier A1 is small (equivalent to mismatching ofcurrent), the circuit is suitable for being mounted in an SOC (system ona chip) memory and a microprocessor. Further, a chopper may be employedto reduce element mismatching of the amplifier A1, or a DEM (dynamicelement matching) may be employed to improve matching of the MOStransistor.

Hereinbefore, according to the reference voltage generating circuit 1according to the first embodiment, by configuring the BGR core circuit10 to have the above-described circuit configuration, it is possible toperform the low voltage output and the low power supply voltageoperation, and to reduce the influence of the offset of the amplifier onthe output voltage V_(BGR). Further, by generating the correctingcurrent I_(COMP) by the non-linear correcting circuit 20 to cause thecurrent to be fed back to the BGR core circuit 10, it is possible tofurther reduce the temperature dependence of the output voltage V_(BGR).

Second Embodiment

FIG. 19 is a circuit diagram illustrating an example of a referencevoltage generating circuit according to a second embodiment.

In FIG. 19, the same reference numerals are given to the same componentsand the like as in the reference voltage generating circuit 1 accordingto the first embodiment, and detailed description thereof will not beshown.

A reference voltage generating circuit 2 shown in FIG. 19 includes a BGRcore circuit 10A and a non-linear correcting circuit 20. The BGR corecircuit 10A has a configuration in which the resistance R5 is removedfrom the BGR core circuit 10 according to the first embodiment.

In the reference voltage generating circuit 2, a feedback destination ofthe correcting current I_(COMP) is the resistance R3. Although there isno particular limitation, in the present embodiment, a configuration isused in which the resistance R3 is divided into a resistance R31 and aresistance R32 and the current I_(COMP) is fed back to a connection nodeof the respective resistances.

The output voltage V_(BGR) in the reference voltage generating circuit 2is as follows.

If R₁=R₂=R₁₂ in a similar way to the first embodiment, Formula 42 isestablished from the Kirchhoff's voltage law at the node of the electricpotential V3.

(Formula 42)

Formula 42

I=2I _(PTAT) +I _(VBE2)  (Formula 42)

Further, Formula 43 is established according to the Thevenin's theorem.

(Formula 43)

Formula 43

V _(BE2) =I _(VBE2)(R ₃₁ +R ₃₂)+I _(COMP) R ₃₂  (Formula 43)

Further, the correcting current I_(COMP) is expressed as Formula 44.Here, with respect to the direction of the correcting current I_(COMP),a direction where the current flows into the resistance R3 from the MOStransistor MP4 is represented as positive, as shown in FIG. 19.

(Formula  44) $\begin{matrix}{{Formula}\mspace{14mu} 44} & \; \\{I_{comp} = \frac{V_{BGR} - V_{{BE}\; 3}}{R_{6}}} & ( {{Formula}\mspace{14mu} 44} )\end{matrix}$

Further, since Formula 45A is established from the Kirchhoff's voltagelaw from the ground (ground node) to the node of the voltage V3, anIPTAT current is expressed as Formula 45B.

$\begin{matrix}{( {{Formula}\mspace{14mu} 45} )\;} & \; \\{{Formula}\mspace{14mu} 45} & \; \\{{V_{{BE}\; 1} + {I_{PTAT}R_{12}}} = V_{{BE}\; 2}} & ( {{Formula}\mspace{14mu} 45A} ) \\{I_{PTAT} = {\frac{V_{{BE}\; 2} - V_{{BE}\; 1}}{R_{12}} = \frac{V_{T}{\ln (n)}}{R_{12}}}} & ( {{Formula}\mspace{14mu} 45B} )\end{matrix}$

If Formula 43 and Formula 45B are substituted in Formula 42 to calculatethe output voltage V_(BGR), Formula 46 is obtained. Here, it is notedthat VCOMP that is the third term in Formula 46 shows a negative value.

     (Formula  46) $\begin{matrix}{\mspace{79mu} {{Formula}\mspace{14mu} 46}} & \; \\{V_{BGR} = {{R_{4}I} = {{R_{4}\{ {{2\frac{V_{T}{\ln (n)}}{R_{12}}} + \frac{V_{{BE}\; 2} - {I_{COMP}R_{32}}}{R_{31} + R_{32}}} \}} = {\underset{\underset{VBGR\_ PTAT}{}}{\frac{R_{4}V_{{BE}\; 2}}{\underset{\underset{VCTAT}{}}{R_{31} + R_{32}}} + {2\frac{R_{4}V_{T}{\ln (n)}}{\underset{\underset{VPTAT}{}}{R_{12}}\;}}} - \frac{R_{4}I_{COMP}R_{32}}{\underset{\underset{VCOMP}{}}{R_{31} + R_{32}}\;}}}}} & ( {{Formula}\mspace{14mu} 46} )\end{matrix}$

FIG. 20 is a diagram illustrating a principle of a method of correctinga non-linear temperature characteristic by the reference voltagegenerating circuit 2.

The reference voltage generating circuit 2 corrects a negativetemperature dependence (first term: VCTAT) of the base-emitter voltageVBE of the bipolar transistor Q2 by a voltage (second term: VPTAT) thatis proportional to the absolute temperature and a non-linear correctingvoltage (third term: VCOMP). The correcting current I_(COMP) has acharacteristic that it increases on high temperature side with referenceto a predetermined temperature T1 in a similar way to the referencevoltage generating circuit 1, but the non-linear correcting voltage(third term: VCOMP) has a characteristic that it becomes negative on thehigh temperature side. Accordingly, in the reference voltage generatingcircuit 2, as shown in FIG. 20, the sum (VBGR_PTAT) of the first termand the second term is optimized so that the temperature coefficient iszero on the high temperature side. Thus, it is possible to reduce thetemperature drift of the output voltage V_(BGR).

The above-described calculation is an approximate calculation in asimilar way to the first embodiment, and precise values of theresistance value, the correcting current value and the like arecalculated by simulation. Further, addition of the start-up circuit andthe low pass filter, and application to a system LSI or the like may beapplied in a similar way to the first embodiment.

Hereinbefore, according to the reference voltage generating circuit 2according to the second embodiment, in a similar way to the referencevoltage generating circuit 1, it is possible to perform the low voltageoutput and the low power supply voltage operation, and to reduce theinfluence of the offset of the amplifier on the output voltage V_(BGR).Further, it is possible to further reduce the temperature dependence ofthe output voltage V_(BGR).

Third Embodiment

FIG. 21 is a circuit diagram illustrating an example of a referencevoltage generating circuit according to a third embodiment.

In FIG. 21, the same reference numerals are given to the same componentsand the like as in the first and second embodiments, and detaileddescription thereof will not be shown.

A reference voltage generating circuit 3 shown in FIG. 21 includes theBGR core circuit 10A and a non-linear correcting circuit 20A. Thenon-linear correcting circuit 20A has a configuration in which thegenerated correcting current I_(COMP) is returned to be output.

In the reference voltage generating circuit 3, a feedback destination ofthe correcting current I_(COMP) is the resistance R3. Although there isno particular limitation, in the present embodiment, a configuration isused in which the resistance R3 is divided into the resistance R31 andthe resistance R32 and the current is fed back to the connection node ofthe respective resistances.

The output voltage V_(BGR) in the reference voltage generating circuit 3is as follows.

With respect to the direction of the correcting current I_(COMP), adirection where the current flows into the MOS transistor MP4 from theresistance R3 is represented as positive, as shown in FIG. 21. Then, ifthe calculation is performed by the same method as in the referencevoltage generating circuit 2 according to the second embodiment, theoutput voltage V_(BGR) is expressed as Formula 47. Here, attentionshould be given the fact that the third term (VCOMP) in Formula 47 is apositive value on high temperature side.

(Formula  47) $\begin{matrix}{{Formula}\mspace{14mu} 47} & \; \\{V_{BGR} = {{R_{4}I} = {{R_{4}\{ {{2\frac{V_{T}{\ln (n)}}{R_{12}}} + \frac{V_{{BE}\; 2} + {I_{COMP}R_{32}}}{R_{31} + R_{32}}} \}} = {\underset{\underset{VBGR\_ PTAT}{}}{\frac{R_{4}V_{{BE}\; 2}}{\underset{\underset{VCTAT}{}}{R_{31} + R_{32}}} + {2\frac{R_{4}V_{T}{\ln (n)}}{\underset{\underset{VPTAT}{}}{R_{12}}\;}}} + \frac{R_{4}I_{COMP}R_{32}}{\underset{\underset{VCOMP}{}}{R_{31} + R_{32}}\;}}}}} & ( {{Formula}\mspace{14mu} 47} )\end{matrix}$

FIG. 22 is a diagram illustrating a principle of a method of correctinga non-linear temperature characteristic by the reference voltagegenerating circuit 3.

The reference voltage generating circuit 3 corrects a negativetemperature dependence (first term: VCTAT) of the base-emitter voltageVBE of the bipolar transistor Q2 by a voltage (second term: VPTAT) thatis proportional to the absolute temperature and a non-linear correctingvoltage (third term: VCOMP). The correcting current I_(COMP) has acharacteristic that it increases on high temperature side with referenceto a predetermined temperature T1 in a similar way to the referencevoltage generating circuit 1, but since the correcting current I_(COMP)is returned by the current mirror circuit that includes the MOStransistors MN3 and MN4, the correcting current I_(COMP) is extractedfrom the connection node of the resistances R31 and R32. Thus, thenon-linear correcting voltage (third term: VCOMP) becomes positive onthe high temperature side. Accordingly, in the reference voltagegenerating circuit 2, as shown in FIG. 22, the sum (VBGR_PTAT) of thefirst term and the second term is optimized so that the temperaturecoefficient is zero on the low temperature side. Thus, it is possible toreduce the temperature drift of the output voltage V_(BGR). Theabove-described calculation is an approximate calculation in a similarway to the first embodiment, and precise values of the resistance value,the correcting current value and the like are calculated by simulation.

Further, addition of the start-up circuit and the low pass filter, andapplication to a system LSI or the like may be applied in a similar wayto the first embodiment.

Hereinbefore, according to the reference voltage generating circuit 3according to the third embodiment, in a similar way to the referencevoltage generating circuit 1, it is possible to perform the low voltageoutput and the low power supply voltage operation, and to reduce theinfluence of the offset of the amplifier on the output voltage V_(BGR).Further, it is possible to further reduce the temperature dependence ofthe output voltage V_(BGR).

Fourth Embodiment

FIG. 23 is a circuit diagram illustrating an example of a referencevoltage generating circuit according to a fourth embodiment.

In FIG. 23, the same reference numerals are given to the same componentsand the like as in the first to third embodiments, and detaileddescription thereof will not be shown.

A reference voltage generating circuit 4 shown in FIG. 23 includes a BGRcore circuit 10B and a non-linear correcting circuit 20B. The BGR corecircuit 10B has a configuration in which the resistance R5 is removedfrom the BGR core circuit 10. The non-linear correcting circuit 20B hasa configuration in which the current mirror circuit of the non-linearcorrecting circuit 20 is a folded current mirror circuit. A bias voltageVbias is supplied to gate terminals of the MOS transistors MP3 and MP4that form the folded current mirror circuit, for example, from a selfbias circuit (not shown) or the like.

In the reference voltage generating circuit 4, a feedback destination ofthe correcting current I_(COMP) is a connection node of the resistanceR2 and the collector terminal of the bipolar transistor Q2.

The output voltage V_(BGR) in the reference voltage generating circuit 4is as follows. Although there is no particular limitation, forsimplicity, the mirror ratio of the correcting current I_(COMP) is setto 1:1.

If R1=R2=R12 in a similar way to the first embodiment, Formula 48A andFormula 48B are established from the approximation of the bipolartransistor.

$\begin{matrix}{( {{Formula}\mspace{14mu} 48} )\;} & \; \\{{Formula}\mspace{14mu} 48} & \; \\{V_{{BE}\; 1} = {V_{T}{\ln ( \frac{I_{1}}{{nI}_{S}} )}}} & ( {{Formula}\mspace{14mu} 48A} ) \\{V_{{BE}\; 2} = {V_{T}{\ln ( \frac{I_{1} + I_{comp}}{I_{S}} )}}} & ( {{Formula}\mspace{14mu} 48B} )\end{matrix}$

Since Formula 49 is established from the Kirchhoff's voltage law fromthe ground (ground node) to the node of the electric potential V3, acurrent I1 may be approximated as Formula 50. Here, it is assumed thatI_(COMP)/I₁<<1.

$\begin{matrix}{\mspace{79mu} ( {{Formula}\mspace{14mu} 49} )} & \; \\{\mspace{79mu} {{Formula}\mspace{14mu} 49}} & \; \\{\mspace{79mu} {V_{{BE}\; 2} = {V_{{BE}\; 1} + {R_{12}I_{1}}}}} & ( {{Formula}\mspace{14mu} 49} ) \\{\mspace{79mu} ( {{Formula}\mspace{14mu} 50} )} & \; \\{\mspace{79mu} {{Formula}\mspace{14mu} 50}} & \; \\{I_{1} = {\frac{V_{{BE}\; 2} - V_{{BE}\; 1}}{R_{12}} = {{\frac{V_{T}}{R_{12}}\{ {{\ln ( \frac{I_{1} + I_{comp}}{I_{S}} )} - {\ln ( \frac{I_{1}}{{nI}_{S}} )}} \}} = {{\frac{V_{T}}{R_{12}}\{ {\ln ( {\frac{I_{1} + I_{comp}}{I_{1}}n} )} \}} = {\frac{V_{T}}{R_{12}}\{ {{\ln (n)} + {\ln ( {1 + \frac{I_{comp}}{I_{1}}} )}} \} \text{∼}\frac{V_{T}}{R_{12}}\{ {{\ln (n)} + \frac{I_{comp}}{I_{1}}} \}}}}}} & ( {{Formula}\mspace{14mu} 50} )\end{matrix}$

Since Formula 50 is a simple quadratic equation, if the quadraticequation is solved, it becomes as Formula 51 and the output voltageV_(BGR) is expressed as Formula 52. Here, it is assumed that Formula 53is established.

$\begin{matrix}{\mspace{79mu} ( {{Formula}{\mspace{11mu} \;}51} )} & \; \\{\mspace{79mu} {{{Formula}\mspace{14mu} 51}{\mspace{580mu} ( {{Formula}{\mspace{11mu} \;}51} )}}} & \; \\{\mspace{79mu} {I_{1} = \frac{\sqrt{{{\ln (n)}^{2}V_{T}^{2}} + {4I_{comp}R_{1}V_{T}}} + {{\ln (n)}V_{T}}}{2R_{12}}}} & \; \\{\mspace{79mu} ( {{Formula}{\mspace{11mu} \;}52} )} & \; \\{\mspace{79mu} {{{Formula}\mspace{14mu} 52}{{\mspace{580mu} \;}( {{Formula}\mspace{14mu} 52} )}}} & \; \\\begin{matrix}{V_{BGR} = {{R_{4}( {\frac{V_{{BE}\; 2}}{R_{3}} + {2I_{1}}} )} = {R_{4}( {\frac{V_{{BE}\; 2}}{R_{5}} + {2\frac{\begin{matrix}{\sqrt{{{\ln (n)}^{2}V_{T}^{2}} + {4I_{comp}R_{1}V_{T}}} +} \\{{\ln (n)}V_{T}}\end{matrix}}{2R_{12}}}} )}}} \\{= {R_{4}( {\frac{V_{{BE}\; 2}}{R_{3}} + \frac{\sqrt{{{\ln (n)}^{2}V_{T}^{2}} + {4I_{comp}R_{1}V_{T}}} + {{\ln (n)}V_{T}}}{R_{12}}} )}} \\{= {R_{4}( {\frac{V_{{BE}\; 2}}{R_{3}} + {\frac{{\ln (n)}V_{t}}{R_{12}}\lbrack {\sqrt{1 + \frac{4I_{comp}R_{12}V_{T}}{{\ln (n)}^{2}V_{T}^{2}}} + 1} \rbrack}} )}} \\{\text{∼}{R_{4}( {\frac{V_{{BE}\; 2}}{R_{3}} + {\frac{{\ln (n)}V_{T}}{R_{12}}\lbrack {2 + \frac{4I_{comp}R_{12}V_{T}}{2{\ln (n)}^{2}V_{T}^{2}}} \rbrack}} )}}\end{matrix} & \; \\{\mspace{79mu} ( {{Formula}{\mspace{11mu} \;}53} )} & \; \\{\mspace{79mu} {{{Formula}{\mspace{11mu} \;}53}{\mspace{596mu} ( {{Formula}{\mspace{11mu} \;}53} )}}} & \; \\{\mspace{79mu} {1\operatorname{>>}\frac{4I_{comp}R_{12}V_{T}}{{\ln (n)}^{2}V_{T}^{2}}}} & \;\end{matrix}$

Accordingly, the output voltage V_(BGR) may be expressed as Formula 54.

$\begin{matrix}( {{Formula}{\mspace{11mu} \;}54} ) & \; \\{{Formula}\mspace{14mu} 54} & \; \\{{V_{BGR}\text{∼}{R_{4}( {\frac{V_{{BE}\; 2}}{R_{3}} + {\frac{{\ln (n)}V_{T}}{R_{12}}\lbrack {2 + \frac{2I_{comp}R_{12}}{{\ln (n)}^{2}V_{T}}} \rbrack}} )}} = {\underset{\underset{VBGR\_ PTAT}{}}{\underset{\underset{VCTAT}{}}{\frac{R_{4}}{R_{3}}V_{{BE}\; 2}} + \underset{\underset{VPTAT}{}}{\frac{2R_{4}}{R_{12}}{\ln (n)}V_{T}}} + \underset{\underset{Vcomp}{}}{\frac{R_{4}2I_{comp}R_{12}}{R_{12}{\ln (n)}}}}} & ( {{Formula}{\mspace{11mu} \;}54} )\end{matrix}$

FIG. 24 is a diagram illustrating a principle of a method of correctinga non-linear temperature characteristic by the reference voltagegenerating circuit 4.

The reference voltage generating circuit 4 corrects a negativetemperature dependence (first term: VCTAT) of the base-emitter voltageVBE of the bipolar transistor Q2 by a voltage (second term: VPTAT) thatis proportional to the absolute temperature and a non-linear correctingvoltage (third term: VCOMP). The correcting current I_(COMP) has acharacteristic that it increases on high temperature side with referenceto a predetermined temperature T1 in a similar way to the referencevoltage generating circuit 1, and the non-linear correcting voltage(third term: VCOMP) becomes positive on the high temperature side.Accordingly, in the reference voltage generating circuit 4, as shown inFIG. 24, the sum (VBGR_PTAT) of the first term and the second term isoptimized so that the temperature coefficient is zero on the lowtemperature side. Thus, it is possible to reduce the temperature driftof the output voltage V_(BGR). The above-described calculation is anapproximate calculation in a similar way to the first embodiment, andprecise values of the resistance value, the correcting current value andthe like are calculated by simulation.

Further, addition of the start-up circuit and the low pass filter, andapplication to a system LSI or the like may be applied in a similar wayto the first embodiment.

Hereinbefore, according to the reference voltage generating circuit 4according to the fourth embodiment, in a similar way to the referencevoltage generating circuit 1, it is possible to perform the low voltageoutput and the low power supply voltage operation, and to reduce theinfluence of the offset of the amplifier on the output voltage V_(BGR).Further, it is possible to further reduce the temperature dependence ofthe output voltage V_(BGR). Further, since the correcting circuit 20Bdoes not have a circuit configuration in which the current mirrorcircuit is stacked on the bipolar transistor Q3 as in the correctingcircuit 20 or the like, the correcting circuit 20B may be operated at alower power supply voltage. The correcting circuit 20B may also beapplied to a reference voltage generating circuit according to anotherembodiment.

Fifth Embodiment

FIG. 25 is a circuit diagram illustrating an example of a referencevoltage generating circuit according to a fifth embodiment.

In FIG. 25, the same reference numerals are given to the same componentsand the like as in the first to fourth embodiments, and detaileddescription thereof will not be shown.

A reference voltage generating circuit 5 shown in FIG. 25 includes a BGRcore circuit 10C and the non-linear correcting circuit 20. The BGR corecircuit 10C has a configuration in which the resistance R4 is dividedinto a resistance R41 and a resistance R42 from the BGR core circuit 10.The reference voltage generating circuit 5 is different from thereference voltage generating circuit 1 in that a feedback destination ofthe correcting current I_(COMP) is a connection node of the resistanceR41 and the resistance R42.

The output voltage V_(BGR) in the reference voltage generating circuit 5is as follows.

If R₁=R₂=R₁₂ in a similar way to the first embodiment, Formula 55 isestablished from the Kirchhoff's voltage law at the node of the electricpotential V3.

(Formula 55)

Formula 55

I=2I _(PTAT) +I _(VBE2)  (Formula 55)

Further, Formula 56 is established.

(Formula 56)

Formula 56

V _(BE2) =I _(VBE2) R ₃  (Formula 56)

Further, the correcting current I_(COMP) is expressed as Formula 57.Here, with respect to the direction of the correcting current I_(COMP),a direction where the current flows into the resistance R4 from the MOStransistor MP4 is represented as positive, as shown in FIG. 25.

$\begin{matrix}( {{Formula}{\mspace{11mu} \;}57} ) & \; \\{{Formula}\mspace{14mu} 57} & \; \\{I_{COMP} = \frac{V_{BGR} - V_{{BE}\; 3}}{R_{6}}} & ( {{Formula}\mspace{14mu} 57} )\end{matrix}$

Further, since Formula 58A is established from the Kirchhoff's voltagelaw from the ground (ground node) to the node of the voltage V3, anIPTAT current is expressed as Formula 58B.

$\begin{matrix}( {{Formula}{\mspace{11mu} \;}58} ) & \; \\{{Formula}\mspace{14mu} 58} & \; \\{{V_{{BE}\; 1} + {I_{PTAT}R_{12}}} = V_{{BE}\; 2}} & ( {{Formula}\mspace{14mu} 58A} ) \\{I_{PTAT} = {\frac{V_{{BE}\; 2} - V_{{BE}\; 1}}{R_{12}} = \frac{V_{T}{\ln (n)}}{R_{12}}}} & ( {{Formula}\mspace{14mu} 58B} )\end{matrix}$

If Formula 56 and Formula 58B are substituted in Formula 55 to calculatethe output voltage V_(BGR) according to the Thevenin's theorem, Formula59 is obtained.

$\begin{matrix}{\mspace{79mu} ( {{Formula}{\mspace{11mu} \;}59} )} & \; \\{\mspace{79mu} {{{Formula}\mspace{14mu} 59} ( {{Formula}{\mspace{11mu} \;}59} )}} & \; \\\begin{matrix}{V_{BGR} = {{{( {R_{41} + R_{42}} )I} + {R_{42}I_{COMP}}} = ( {R_{41} + R_{42}} )}} \\{{\{ {{2\frac{V_{T}{\ln (n)}}{R_{12}}} + \frac{V_{{BE}\; 2}}{R_{3}}} \} + {R_{42}I_{COMP}}}} \\{= {\underset{\underset{VBGR\_ PTAT}{}}{\underset{\underset{VCTAT}{}}{( {R_{41} + R_{42}} )\frac{V_{{BE}\; 2}}{R_{3}}} + \underset{\underset{VPTAT}{}}{( {R_{41} + R_{42}} )\{ {2\frac{V_{T}{\ln (n)}}{R_{12}}} \}}} + \underset{\underset{VCOMP}{}}{R_{42}I_{COMP}}}}\end{matrix} & \;\end{matrix}$

FIG. 26 is a diagram illustrating a principle of a method of correctinga non-linear temperature characteristic by the reference voltagegenerating circuit 5.

The reference voltage generating circuit 5 corrects a negativetemperature dependence (first term: VCTAT) of the base-emitter voltageVBE of the bipolar transistor Q2 by a voltage (second term: VPTAT) thatis proportional to the absolute temperature and a non-linear correctingvoltage (third term: VCOMP). Since the correcting current I_(COMP) has acharacteristic that it increases on high temperature side with referenceto a predetermined temperature T1 in a similar way to the referencevoltage generating circuit 1, the non-linear correcting voltage (thirdterm: VCOMP) becomes positive on the high temperature side, which isadded as a Thevenin voltage. Accordingly, in the reference voltagegenerating circuit 5, as shown in FIG. 26, the sum (VBGR_PTAT) of thefirst term and the second term is optimized so that the temperaturecoefficient is zero on the low temperature side. Thus, it is possible toreduce the temperature drift of the output voltage V_(BGR).

The above-described calculation is an approximate calculation in asimilar way to the first embodiment, and precise values of theresistance value, the correcting current value and the like arecalculated by simulation.

Further, addition of the start-up circuit and the low pass filter, andapplication to a system LSI or the like may be applied in a similar wayto the first embodiment.

Hereinbefore, according to the reference voltage generating circuit 5according to the fifth embodiment, in a similar way to the referencevoltage generating circuit 1, it is possible to perform the low voltageoutput and the low power supply voltage operation, and to reduce theinfluence of the offset of the amplifier on the output voltage V_(BGR).Further, it is possible to further reduce the temperature dependence ofthe output voltage V_(BGR). Further, a method of adding the correctingcurrent to the resistance R4 that generates the output voltage V_(BGR)shown in the present embodiment may also be applied to the BGR circuithaving a configuration in which the current is converted into thevoltage and output as in PTL 2, and thus, it is similarly possible toreduce the temperature dependence of the output voltage V_(BGR).

Sixth Embodiment

FIG. 27 is a circuit diagram illustrating an example of a referencevoltage generating circuit according to a sixth embodiment.

In FIG. 27, the same reference numerals are given to the same componentsand the like as in the reference voltage generating circuit 1 accordingto the first embodiment, and detailed description thereof will not beshown.

A reference voltage generating circuit 6 shown in FIG. 27 includes theBGR core circuit 10 and a non-linear correcting circuit 20C. Thenon-linear correcting circuit 20C generates the correcting currentI_(COMP) using a characteristic of a sub threshold region of a MOStransistor, unlike the non-linear correcting circuit 20 according to thefirst embodiment. The correcting circuit 20C includes an amplifier A2that receives the output voltage V_(BGR) of the BGR core circuit 10 asan input and buffers the received voltage to be output, an N-type MOStransistor MN6 that receives an output voltage of the amplifier A2 as aninput at a gate terminal thereof, an N-type MOS transistor MN5 in whicha drain terminal at the same electric potential as that of a gateterminal thereof is connected to a source terminal of the MN6, aresistance R6 that is provided between a source terminal of the MN5 andthe ground node, and P-type MOS transistors MP3 and MP4 that form acurrent mirror circuit for outputting a correcting current on the basisof a current that flows in the MN6.

The correcting current I_(COMP) may be expressed as Formula 60 whengate-source voltages of the MN5 and MN6 are represented as V_(GS5) andV_(GS6).

$\begin{matrix}( {{Formula}{\mspace{11mu} \;}60} ) & \; \\{{Formula}\mspace{14mu} 60} & \; \\{I_{COMP} = \frac{V_{BGR} - ( {V_{{GS}\; 5} + V_{{GS}\; 6}} )}{R_{6}}} & ( {{Formula}\mspace{14mu} 60} )\end{matrix}$

Since the characteristic of the sub threshold region of the MOStransistor is a characteristic that is close to an I_(c)−V_(BE)characteristic of the bipolar transistor, the MOS transistors MN5 andMN6 are operated in the sub threshold region, and thus, in a similar wayto the correcting circuit 20 or the like, it is possible to generate thecorrecting current I_(COMP) that increases on high temperature side withreference to a predetermined temperature. Thus, in a similar way to thefirst embodiment, it is possible to improve the non-linear temperaturedependence of the output voltage.

The number of stages of the MOS transistors may be changed according tothe characteristic of the sub threshold region of the MOS transistor. InFIG. 27, an example in which one MOS transistor MN5 is inserted and thecorrecting current is generated by two-stages of MOS transistors isshown as an example. Further, in FIG. 27, the amplifier A2 is insertedas a buffer, but the output voltage V_(BGR) of the BGR core circuit 10may be directly input to a gate side of the MN 6.

A feedback destination of the correcting current I_(COMP) generated bythe method according to the present embodiment is not limited to theresistance R5, and may be the resistance R3, a node of an electricpotential VB, or the like, as shown in the other embodiments.

Further, addition of the start-up circuit and the low pass filter, andapplication to a system LSI or the like may be applied in a similar wayto the other embodiments.

Hereinbefore, according to the reference voltage generating circuit 6according to the sixth embodiment, in a similar way to the referencevoltage generating circuit 1, it is possible to perform the low voltageoutput and the low power supply voltage operation, and to reduce theinfluence of the offset of the amplifier on the output voltage V_(BGR).Further, it is possible to further reduce the temperature dependence ofthe output voltage V_(BGR).

Seventh Embodiment

FIG. 28 is a circuit diagram illustrating an example of a BGR corecircuit according to a seventh embodiment.

A BGR core circuit 10D shown in FIG. 28 is an example of another circuitconfiguration of the BGR core circuit in the above-described referencevoltage generating circuit 1. In FIG. 28, the same reference numeralsare given to the same components and the like as in the referencevoltage generating circuit 1 according to the first embodiment, anddetailed description thereof will not be shown.

The BGR core circuit 10D has a configuration in which the resistance R5and the resistance R3 are removed from the BGR core circuit 10 and acircuit of an output stage that generates the output voltage V_(BGR) ischanged. Specifically, the circuit of the output stage includes abipolar transistor Q4 that is grounded at an emitter terminal thereofand is diode-connected; a resistance R9 that is grounded at one terminalthereof; a resistance R8 that is provided between a collector side ofthe bipolar transistor Q4 and the other end of the resistance R9; andMOS transistors MP2 and MP5 that are connected on their drain sides tonodes to which both ends of the resistance R8 are connected and have thesame electric potential as that of the gate terminal of the MOStransistor MP1 at their gate terminals.

The output voltage V_(BGR) of the BGR core circuit 10D is as follows.

If R₁=R₂=R₁₂, in a similar way to the first embodiment, Formula 61,Formula 62A and Formula 62B are established in FIG. 28.

$\begin{matrix}( {{Formula}{\mspace{11mu} \;}61} ) & \; \\{{Formula}\mspace{14mu} 61} & \; \\{{V_{{BE}\; 1} + {R_{2}I_{PTAT}}} = V_{{BE}\; 2}} & ( {{Formula}\mspace{14mu} 61} ) \\( {{Formula}\mspace{14mu} 62} ) & \; \\{{Formula}\mspace{14mu} 62} & \; \\{V_{{BE}\; 1} = {V_{T}{\ln ( \frac{I_{PTAT}}{{nI}_{S}} )}}} & ( {{Formula}\mspace{14mu} 62A} ) \\{V_{{BE}\; 2} = {V_{T}{\ln ( \frac{I_{PTAT}}{I_{S}} )}}} & ( {{Formula}\mspace{14mu} 62B} )\end{matrix}$

The current I_(PTAT) is expressed as Formula 63 from Formula 61, Formula62A and Formula 62B. Further, the current I is expressed as Formula 64from the Kirchhoff's voltage law.

$\begin{matrix}( {{Formula}{\mspace{11mu} \;}63} ) & \; \\{{Formula}\mspace{14mu} 63} & \; \\{I_{PTAT} = {\frac{V_{{BE}\; 2} - V_{{BE}\; 1}}{R_{2}} = \frac{V_{T}{\ln (n)}}{R_{2}}}} & ( {{Formula}\mspace{14mu} 63} ) \\( {{Formula}\mspace{14mu} 64} ) & \; \\{{Formula}\mspace{14mu} 64} & \; \\{I = {2I_{PTAT}}} & ( {{Formula}\mspace{14mu} 64} )\end{matrix}$

If the Kirchhoff's voltage law is applied to the output stage of FIG.28, a current I_(R8) is expressed as Formula 65. Further, since acurrent that is the sum of the current I_(R8) and a drain current I ofthe MP5 flows through the resistance R9, the V_(BGR) is expressed asFormula 66.

$\begin{matrix}( {{Formula}{\mspace{11mu} \;}65} ) & \; \\{{Formula}\mspace{14mu} 65} & \; \\{I_{R\; 8} = \frac{V_{{BE}\; 4} - V_{BGR}}{R_{8}}} & ( {{Formula}\mspace{14mu} 65} ) \\( {{Formula}\mspace{14mu} 66} ) & \; \\{{Formula}\mspace{14mu} 66} & \; \\{V_{BGR} = {R_{9}( {I + I_{R\; 8}} )}} & ( {{Formula}\mspace{14mu} 66} )\end{matrix}$

Accordingly, Formula 67 is obtained from Formula 63 to Formula 66, andfrom Formula 67, the output voltage V_(BGR) is expressed as Formula 68.

$\begin{matrix}( {{Formula}{\mspace{11mu} \;}67} ) & \; \\{{Formula}\mspace{14mu} 67} & \; \\{V_{BGR} = {R_{9}( {{2\frac{V_{T}{\ln (n)}}{R_{2}}} + \frac{V_{{VBE}\; 4} - V_{BGR}}{R_{8}}} )}} & ( {{Formula}\mspace{14mu} 67} ) \\( {{Formula}\mspace{14mu} 68} ) & \; \\{{Formula}\mspace{14mu} 68} & \; \\{V_{BGR} = {\frac{R_{9}}{R_{8} + R_{9}}\{ {V_{{BE}\; 3} + {\frac{2R_{8}}{R_{12}}V_{T}{\ln (n)}}} \}}} & ( {{Formula}\mspace{14mu} 68} )\end{matrix}$

In Formula 68, if R₄/(R₃+R₄)<1, the output voltage V_(BGR) may be 1.0 Vor lower. Accordingly, according to the BGR core circuit 10D, in asimilar way to the BGR core circuit 10, it is possible to perform thelow voltage output and the low power supply voltage operation, and toreduce the influence of the offset of the amplifier on the outputvoltage V_(BGR).

Further, as understood from Formula 64, the current I output from theMOS transistor MP1 does not include a current having a non-lineartemperature characteristic based on the base-emitter voltage VBE. Thatis, according to the BGR core circuit 10D, it is possible to generateand output a current IPTAT that is proportional to the temperature.

FIG. 29 is a circuit diagram illustrating an example of a BGR corecircuit that includes a voltage generating section that generates avoltage (VPTAT) that is proportional to the absolute temperature.

A BGR core circuit 10E shown in FIG. 29 includes a PTAT voltagegenerating section that includes a P-channel MOS transistor MP6 in whicha source electric potential and a gate electric potential are the sameas in MP1 and a resistance R10 that is provided between a drain terminalof the MP6 and the ground node, in addition to the BGR core circuit 10D.Accordingly, it is possible to easily generate the PTAT voltage.

FIG. 30 is a block diagram illustrating an example of a semiconductorintegrated circuit device to which a reference voltage generatingcircuit that includes the BGR core circuit 10E and a non-linearcorrecting circuit is applied.

Although there is no particular limitation, a semiconductor integratedcircuit device 101 is a system LSI in which a power supply circuit isinstalled, for example.

The semiconductor integrated circuit device 101 has a configuration inwhich a temperature sensor 52 is added to the semiconductor integratedcircuit device (system LSI) 100 described above in FIG. 18. Thetemperature sensor 52 includes a reference voltage generating circuit 54and an AD converter 53. The reference voltage generating circuit 54includes the BGR core circuit 10E and the non-linear correcting circuit20, for example.

According to the above-described BGR core circuits 10D and 10E accordingto the seventh embodiment, in a similar way to the BGR circuit 10according to the first embodiment, it is possible to perform the lowvoltage output and the low power supply voltage operation, and to reducethe influence of the offset of the amplifier on the output voltageV_(BGR). Further, it is possible to easily generate the PTAT voltage.

Eighth Embodiment

FIG. 31 is a circuit diagram illustrating an example of a BGR corecircuit according to an eighth embodiment of the invention.

A BGR core circuit 10F shown in FIG. 31 is an example of another circuitconfiguration of the BGR core circuit in the above-described referencevoltage generating circuit 1. In FIG. 31, the same reference numeralsare given to the same components and the like as in the referencevoltage generating circuit 1 according to the first embodiment, anddetailed description thereof will not be shown.

The BGR core circuit 10F has a configuration in which a resistance R81is added on a collector side of the bipolar transistor Q4 with respectto the BGR core circuit 10D.

Accordingly, in a similar way to the BGR circuit 10D, it is possible toperform the low voltage output and the low power supply voltageoperation, and to reduce the influence of the offset of the amplifier onthe output voltage V_(BGR). Further, it is possible to easily generatethe VPTAT voltage.

Ninth Embodiment

FIG. 32 is a circuit diagram illustrating an example of a BGR corecircuit according to a ninth embodiment of the invention.

A BGR core circuit 10G shown in FIG. 32 is an example of another circuitconfiguration of the BGR core circuit in the above-described referencevoltage generating circuit 1. In FIG. 32, the same reference numeralsare given to the same components and the like as in the referencevoltage generating circuit 1 according to the first embodiment, anddetailed description thereof will not be shown.

The BGR core circuit 10G has a configuration in which the resistance R5and the resistance R3 are removed from the BGR core circuit 10 and acircuit of an output stage that generates the output voltage V_(BGR) ismodified. Specifically, the circuit of the output stage includes abipolar transistor Q4 that is grounded at an emitter terminal thereofand is diode-connected; a resistance R9 that is grounded at one terminalthereof; a resistance R11 that is provided between a collector side ofthe bipolar transistor Q4 and the other end of the resistance R9; and aMOS transistor MP5 that is connected to a connection node of theresistances R11 and R9 on a drain side thereof and includes a gateterminal at the same electric potential as that of the gate terminal ofthe MOS transistor Mph.

The output voltage V_(BGR) of the BGR core circuit 10G is expressed asFormula 69.

$\begin{matrix}( {{Formula}{\mspace{11mu} \;}69} ) & \; \\{{Formula}\mspace{14mu} 69} & \; \\{V_{BGR} = {\frac{R_{9}}{R_{11} + R_{9}}\{ {V_{{BE}\; 3} + {\frac{2R_{11}}{R_{12}}V_{T}{\ln (n)}}} \}}} & ( {{Formula}\mspace{14mu} 69} )\end{matrix}$

FIG. 33 is a diagram illustrating an example of a circuit that includesa voltage generating section that generates a voltage (VPTAT) that isproportional to the absolute temperature in the BGR core circuit 10G inFIG. 32.

A BGR core circuit 10H shown in FIG. 33 includes a PTAT voltagegenerating section that includes a P-channel MOS transistor MP6 in whicha source electric potential and a gate electric potential are the sameas in MP1 and a resistance R10 that is provided between a drain terminalof the MP6 and the ground node, in addition to the BGR core circuit 10G.Accordingly, it is possible to easily generate the PTAT voltage.

According to the above-described BGR core circuit 10H according to theninth embodiment, in a similar way to the BGR core circuit 10D, it ispossible to perform the low voltage output and the low power supplyvoltage operation, and to reduce the influence of the offset of theamplifier on the output voltage V_(BGR). Further, it is possible toeasily generate the PTAT voltage.

Tenth Embodiment

FIG. 34 is a circuit diagram illustrating an example of a BGR corecircuit according to a tenth embodiment of the invention.

A BGR core circuit 10I shown in FIG. 34 is an example of another circuitconfiguration of the BGR core circuit in the above-described referencevoltage generating circuit 1. In FIG. 34, the same reference numeralsare given to the same components and the like as in the referencevoltage generating circuit 1 according to the first embodiment, anddetailed description thereof will not be shown.

The BGR core circuit 10I has a configuration in which the resistance R5is removed from the BGR core circuit 10. Thus, the common input voltagesof the amplifier A1 are low compared with the BGR core circuit 10. Theoutput voltage V_(BGR) of the BGR core circuit 10I is the same as in theBGR core circuit 10. According to the BGR core circuit 10I, it ispossible to perform the low voltage output and the low power supplyvoltage operation, and to reduce the influence of the offset of theamplifier on the output voltage V_(BGR).

Eleventh Embodiment

FIG. 35 is a circuit diagram illustrating an example of a BGR corecircuit according to an eleventh embodiment of the invention.

A BGR core circuit 10J shown in FIG. 35 is an example of another circuitconfiguration of the BGR core circuit in the above-described referencevoltage generating circuit 1. In FIG. 35, the same reference numeralsare given to the same components and the like as in the referencevoltage generating circuit 1 according to the first embodiment, anddetailed description thereof will not be shown.

The BGR core circuit 10J has a configuration in which the resistance R5is removed from the BGR core circuit 10 and a resistance R7 is providedbetween the drain terminal of the MOS transistor MP1 and the connectionnode of the resistances R1 and R2. Thus, it is possible to adjust thecommon input voltages of the amplifier A1. The output voltage V_(BGR) ofthe BGR core circuit 10J is the same as in the BGR core circuit 10.According to the BGR core circuit 10J, it is possible to perform the lowvoltage output and the low power supply voltage operation, and to reducethe influence of the offset of the amplifier on the output voltageV_(BGR).

Twelfth Embodiment

FIG. 36 is a circuit diagram illustrating an example of a BGR corecircuit according to a twelfth embodiment of the invention.

The BGR core circuit 10K shown in FIG. 36 is an example of anothercircuit configuration of the BGR core circuit in the above-describedreference voltage generating circuit 1. In FIG. 36, the same referencenumerals are given to the same components and the like as in thereference voltage generating circuit 1 according to the firstembodiment, and detailed description thereof will not be shown.

The BGR core circuit 10K has a configuration in which the resistance R7is provided between the drain terminal of the MOS transistor MP1 and theconnection node of the resistances R1 and R2, to the BGR core circuit10. Thus, it is possible to adjust the common input voltages of theamplifier A1. The output voltage V_(BGR) of the BGR core circuit 10K isthe same as in the BGR core circuit 10. According to the BGR corecircuit 10K, it is possible to perform the low voltage output and thelow power supply voltage operation, and to reduce the influence of theoffset of the amplifier on the output voltage V_(BGR).

Thirteenth Embodiment

FIG. 37 is a circuit diagram illustrating an example of a BGR corecircuit according to a thirteenth embodiment.

The BGR core circuit 10L shown in FIG. 37 is an example of anothercircuit configuration of the BGR core circuit in the above-describedreference voltage generating circuit 1. In FIG. 37, the same referencenumerals are given to the same components and the like as in thereference voltage generating circuit 1 according to the firstembodiment, and detailed description thereof will not be shown.

The BGR core circuit 10L has a configuration in which the resistance R5is removed from the BGR core circuit 10 and the voltages on thecollector sides of the bipolar transistors Q1 and Q2 are divided to beinput to an amplifier A3. In FIG. 37, a method of dividing the voltagesby resistances R12 and R13 and resistances R14 and R15 is shown as anexample. Thus, it is possible to lower the common input voltages of theamplifier A3, and to easily design the amplifier A3.

FIG. 38 is a circuit diagram illustrating an example of the amplifierA3.

As shown in FIG. 38, by lowering the common input voltages of theamplifier, it is possible to use a differential amplifier that uses aP-channel MOS transistor at an input stage, as the amplifier A3. In FIG.38, a voltage Vbp represents a bias voltage.

The output voltage V_(BGR) of the BGR core circuit 10L is the same as inthe BGR core circuit 10. According to the BGR core circuit 10L, it ispossible to perform the low voltage output and the low power supplyvoltage operation, and to reduce the influence of the offset of theamplifier on the output voltage V_(BGR).

A method of dividing and adjusting the common input voltages of theamplifier A3 (A1) may be applied to the BGR core circuit according tothe other embodiments. Further, in the present embodiment, an example ofa configuration in which the resistance R5 is removed is shown, but theresistance R5 may be connected as it is.

Fourteenth Embodiment

FIG. 39 is a circuit diagram illustrating an example of a BGR corecircuit according to a fourteenth embodiment.

A BGR core circuit 10M shown in FIG. 39 is an example of another circuitconfiguration of the BGR core circuit in the above-described referencevoltage generating circuit 1. In FIG. 39, the same reference numeralsare given to the same components and the like as in the referencevoltage generating circuit 1 according to the first embodiment, anddetailed description thereof will not be shown.

The BGR core circuit 10M has a configuration in which the resistance R5is removed from the BGR core circuit 10, a resistance R16 is providedbetween a source terminal of the MOS transistor MP1 and the power sourceVcc and a resistance R17 is provided between a source terminal of theMOS transistor MP2 and the power source Vcc. Accordingly, it is possibleto reduce mismatching of the current of the MOS transistor MP1 and thecurrent of the MOS transistor MP2 by source degeneration.

The output voltage V_(BGR) of the BGR core circuit 10L is the same as inthe BGR core circuit 10. According to the BGR core circuit 10L, it ispossible to perform the low voltage output and the low power supplyvoltage operation, and to reduce the influence of the offset of theamplifier on the output voltage V_(BGR).

A method of inserting the degeneration resistances R16 and R17 may beapplied to the BGR core circuit according to the other embodiments.Further, in the present embodiment, an example of a configuration inwhich the resistance R5 is removed is shown, but the resistance R5 maybe connected as it is.

Fifteenth Embodiment

FIG. 40 is a circuit diagram illustrating an example of a BGR corecircuit according to a fifteenth embodiment.

A BGR core circuit 10N shown in FIG. 40 is an example of another circuitconfiguration of the BGR core circuit in the above-described referencevoltage generating circuit 1. In FIG. 40, the same reference numeralsare given to the same components and the like as in the referencevoltage generating circuit 1 according to the first embodiment, anddetailed description thereof will not be shown.

The BGR core circuit 10N is a circuit in which PNP bipolar transistorsare used, unlike the BGR core circuit 10. A specific circuitconfiguration thereof is as follows. As shown in FIG. 40, the BGR corecircuit 10N includes a pair of PNP bipolar transistors Q1P and Q2P thatare connected in common at emitter terminals thereof; resistances R1 andR2 that are connected in common to a base terminal of the bipolartransistor Q2P at one end thereof and are connected to collectorterminals of the bipolar transistors Q1P and Q2P at the other endsthereof; and a resistance R3 that is provided between the base terminalof the bipolar transistor Q2P and a power supply Vcc. Further, the BGRcore circuit 10 includes a differential amplifier A1 that receives, asinputs, respective electric potentials on the collector sides of thebipolar transistors Q1 and Q2, respectively; N-channel MOS transistorsMN7 and MN8 that receive an output voltage of the differential amplifierA1 as an input at a gate terminal thereof and include a source terminalconnected to the ground node; and a resistance R4 that is providedbetween a drain terminal of the MOS transistor MN8 and the power supplyVcc. As the drain terminal of the MOS transistor MN7 is connected to aconnection node of the resistances R1 and R2, a feedback loop is formed.Further, in the bipolar transistors Q1P and Q2P, the emitter area of thebipolar transistor Q1P is larger than the emitter area of the bipolartransistor Q2P by n (n is an integer of 2 or more) times. That is, whenthe same current flows in the bipolar transistors Q1P and Q2P, theemitter current density of the bipolar transistor Q2P is set to be ntimes the emitter current density of the transistor Q1P.

Here, if R₁=R₂=R₁₂, I_(PTAT) is expressed as Formula 70, and thus, theoutput voltage V_(BGR) of the BGR core circuit 10N is expressed asFormula 71.

$\begin{matrix}( {{Formula}{\mspace{11mu} \;}70} ) & \; \\{{Formula}\mspace{14mu} 70} & \; \\{I_{PTAT} = \frac{V_{T}{\ln (n)}}{R_{12}}} & ( {{Formula}\mspace{14mu} 70} ) \\( {{Formula}\mspace{14mu} 71} ) & \; \\{{Formula}\mspace{14mu} 71} & \; \\{V_{BGR} = {{V_{CC} - {2R_{4}I_{PTAT}}} = {V_{CC} - {2R_{4}\frac{V_{T}{\ln (n)}}{R_{12}}}}}} & ( {{Formula}\mspace{14mu} 71} )\end{matrix}$

According to the BGR core circuit 10N that has a configuration in whichthe BGR core circuit 10 is inverted, in a similar way to the BGR corecircuit 10, it is possible to perform the low voltage output and the lowpower supply voltage operation, and to reduce the influence of theoffset of the amplifier on the output voltage V_(BGR).

Sixteenth Embodiment

FIG. 41 is a circuit diagram illustrating an example of a BGR corecircuit according to a sixteenth embodiment.

A BGR core circuit 10O shown in FIG. 41 is an example of another circuitconfiguration of the BGR core circuit in the above-described referencevoltage generating circuit 1. In FIG. 41, the same reference numeralsare given to the same components and the like as in the referencevoltage generating circuit 1 according to the first embodiment, anddetailed description thereof will not be shown.

The BGR core circuit 10O has a configuration in which the resistance R5is inserted between a connection node of the resistance R1 and theresistance R2 and a drain terminal of MN7 with respect to the BGR corecircuit 10N according to the fifteenth embodiment. Accordingly, it ispossible to adjust the common input voltages of the amplifier A1 to beincreased. The output voltage V_(BGR) of the BGR core circuit 10O is thesame in the BGR core circuit 10N. According to the BGR core circuit 100,it is possible to perform the low voltage output and the low powersupply voltage operation, and to reduce the influence of the offset ofthe amplifier on the output voltage V_(BGR).

Seventeenth Embodiment

FIG. 42 is a circuit diagram illustrating an example of a BGR corecircuit according to a seventeenth embodiment.

A BGR core circuit 10P shown in FIG. 42 is an example of another circuitconfiguration of the BGR core circuit in the above-described referencevoltage generating circuit 1. In FIG. 42, the same reference numeralsare given to the same components and the like as in the referencevoltage generating circuit 1 according to the first embodiment, anddetailed description thereof will not be shown.

The BGR core circuit 10P has a configuration in which the resistance R5is inserted between a connection node of the resistance R1 and theresistance R2 and a drain terminal of MN7 and the resistance R7 isinserted between a connection node of the bipolar transistors Q1P andQ2P and the power supply Vcc with respect to the BGR core circuit 10Naccording to the fifteenth embodiment. Accordingly, it is possible toadjust the common input voltages of the amplifier A1. The output voltageV_(BGR) of the BGR core circuit 10P is the same in the BGR core circuit10N. According to the BGR core circuit 10P, it is possible to performthe low voltage output and the low power supply voltage operation, andto reduce the influence of the offset of the amplifier on the outputvoltage V_(BGR).

Eighteenth Embodiment

FIG. 43 is a circuit diagram illustrating an example of a BGR corecircuit according to an eighteenth embodiment.

A BGR core circuit 10Q shown in FIG. 43 is an example of another circuitconfiguration of the BGR core circuit in the above-described referencevoltage generating circuit 1. In FIG. 43, the same reference numeralsare given to the same components and the like as in the referencevoltage generating circuit 1 according to the first embodiment, anddetailed description thereof will not be shown.

The BGR core circuit 10Q has a configuration in which the output voltageV_(BGR) is generated on the basis of a current obtained by inverting thecurrent that flows in MN8, unlike the BGR core circuit 10N according tothe fifteenth embodiment. Specifically, the BGR core circuit 10Q furtherincludes a current mirror circuit (MP8 and MP9) that generates a currentI on the basis of the current that flows in MN8 and supplies thegenerated current to the resistance R4.

The BGR core circuits in the fifteenth embodiment to the seventeenthembodiment are methods of obtaining the output voltages V_(BGR) based onthe power supply VCC, but according to the BGR core circuit 10Qaccording to the present embodiment, it is possible to obtain an outputvoltage based on the ground. Further, in a similar way to the BGR corecircuit 10N or the like, it is possible to achieve the low voltageoutput and the low power supply voltage operation, and to reduce theinfluence of the offset of the amplifier on the output voltage V.

In the present embodiment, a configuration example in which theresistances R5 and R6 are inserted is shown, but a configuration inwhich any one or both of the resistances R5 and R6 are removed may beused.

Nineteenth Embodiment

FIG. 44 is a circuit diagram illustrating an example of a referencevoltage generating circuit according to a nineteenth embodiment.

A reference voltage generating circuit 7 shown in FIG. 44 has aconfiguration in which a non-linear correction is performed in a BGRcore circuit having an output of about 1.2 V. Although there is noparticular limitation, the BGR core circuit shown in FIG. 5 is shown asan example of the BGR core circuit having the output of about 1.2 V inFIG. 44.

The reference voltage generating circuit 7 shown in FIG. 44 includes aBGR core circuit 71 and a non-linear correcting circuit 72.

The BGR core circuit 71 has a circuit configuration in which the BGRcore circuit in FIG. 5 is used as a base as described above. A specificconfiguration thereof is as follows. The BGR core circuit 71 shown inFIG. 44 includes a pair of NPN bipolar transistors Q1 and Q2 that areconnected in common at base terminals thereof; a resistance R22 that isprovided between a collector terminal of the bipolar transistor Q2 and apower supply Vcc; a resistance R21 that is provided between a collectorterminal of the bipolar transistor Q1 and the power supply Vcc; aresistance R20 that is provided between an emitter terminal of thebipolar transistor Q1 and an emitter terminal of the bipolar transistorQ2; a resistance R23 that is provided between the emitter terminal ofthe bipolar transistor Q2 and the ground (ground node). Further, the BGRcore circuit includes a differential amplifier A1 that receives, asinputs, respective electric potentials on the collector sides of thebipolar transistors Q1 and Q2, respectively and is connected to the basesides of the bipolar transistors Q1 and Q2 at an output thereof. In thebipolar transistors Q1 and Q2, the emitter area of the bipolartransistor Q1 is larger than the emitter area of the bipolar transistorQ2 by n (n is an integer of 2 or more) times. That is, when the samecurrent flows in the bipolar transistors Q1 and Q2, the emitter currentdensity of the bipolar transistor Q2 is set to be n times the emittercurrent density of the transistor Q1. Further, the resistance R23 isdivided into a resistance R23A and a resistance R23B, and a correctingcurrent I_(COMP) is supplied to a connection node of both theresistances.

The correcting circuit 72 has a configuration in which the correctingcurrent I_(COMP) is generated from bipolar transistors Q5 to Q8 and theresistance R6 on the basis of the output voltage V_(BGR) and thecorrecting current I_(COMP) is fed back to the BGR core by a currentmirror circuit that includes MP11 and MP12. The correcting currentI_(COMP) is expressed as Formula 72 by the correcting circuit 72.

$\begin{matrix}( {{Formula}{\mspace{11mu} \;}72} ) & \; \\{{Formula}\mspace{14mu} 72} & \; \\{I_{COMP} = \{ \begin{matrix}{0\mspace{14mu} ( {V_{BGR} \leq {2V_{{{BE}\; 5},7}}} )} \\{\frac{V_{BGR} - {2V_{{{BE}\; 5},7}}}{2R_{6}}( {V_{BGR} \geq {2V_{{{BE}\; 5},7}}} )}\end{matrix} } & ( {{Formula}\mspace{14mu} 72} )\end{matrix}$

A principle of generation of the correcting current I_(COMP) is the sameas in the correcting circuit 20 according to the first embodiment, butin the case of the BGR core circuit 71, since the output voltage V_(BGR)is about 1.2 V, by forming the bipolar transistors Q5 and Q7 (Q6 and Q8)in a double-stage structure, a base-emitter voltage VBE becomes twotimes, to thereby generate a preferable correcting current I_(COMP).Here, VBE is set to be two times in consideration of a case where VBE ofthe bipolar transistor is about 0.7 Vat low temperature and about 0.35 Vat high temperature, and thus, the number of stages of the bipolartransistors Q5 and Q7 (Q6 and Q8) is adjusted according to the value ofthe output voltage V_(BGR) and the value of VBE.

The above calculation is an approximate calculation. In actuality, aloop is formed between the BGR core circuit 71 and the correctingcircuit 72 to cause feedback, and thus, the values of the resistance,the correcting current I_(COMP) and the like show some variances fromthe above calculation. Precise values may be calculated by simulation.

FIGS. 45A to 45D are diagrams illustrating a principle of a method ofcorrecting a non-linear temperature characteristic by the referencevoltage generating circuit 7.

VBGR_PTAT shown in FIG. 45A shows an example of a waveform in a casewhere only correction using the voltage VPTAT that is proportional tothe absolute temperature is performed for the base-emitter voltage VBEwhen the correcting current I_(COMP) is neglected. Further, the voltageVBGR_PTAT has a bowl shape, and shows a case where a constant of eachelement is adjusted so that the temperature at which a temperaturecoefficient is zero is achieved on low temperature side. Further, inFIG. 45B, the correcting current I_(COMP) is shown. In FIG. 45C, anexample of a waveform in a case where the correcting voltage VCOMP isadded to the output voltage VBGR_PTAT is shown.

As described above, in order to reduce the temperature drift of thevoltage VBGR_PTAT that has the non-linear temperature dependence, acorrection method of adding a current I_(PTAT) ² that is proportional tothe square of the absolute temperature may be considered, for example.However, in the non-linear correction method of adding the currentI_(PTAT) ² using the absolute temperature 0 K as a starting point, it isdifficult to obtain a current or a voltage that is rapidly changed in atemperature range (for example, temperature range that is necessary inspecification, or the like) in which the correction is to be performed.Thus, in the reference voltage generating circuit 7 according to thepresent embodiment, in a similar way to the reference voltage generatingcircuit 1, the correcting current I_(COMP) in which a characteristicthereof is changed with reference to a predetermined temperature T1 isgenerated, and the correcting voltage VCOMP based on the correctingcurrent I_(COMP) is added to the voltage VBGR_PTAT to perform thenon-linear correction. Accordingly, as shown in FIG. 45D, it is possibleto reduce the temperature drift in the predetermined temperature range.Further, as shown in FIGS. 45A to 45D, it is possible to control theinclination of the correcting current I_(COMP) by the value of theresistance R6.

A waveform example of FIG. 45C is made to emphasize the waveform of theoutput voltage V_(BGR) after the non-linear correction, and inactuality, since the temperature T1 at which the size relationshipbetween “V_(BGR)” and “2V_(BE5, 7)” is reversed is not discontinuous butcontinuous, the output voltage V_(BGR) becomes a smooth curve as shownin FIG. 45D.

Further, if the term of “V_(BGR)−2 V_(BE5, 7)” in Formula 72 isapproximately expressed as a characteristic obtained by subtracting thebase-emitter voltage VBE of the non-linear temperature characteristicfrom the voltage V_(BGR) that is corrected in a linear form (PTAT),which draws a curve that also includes a higher term. In order to reducethe temperature drift at a predetermined temperature range, the curvemay be monotonically increased as in a characteristic indicated by asolid line or a dashed line shown in FIG. 45B, and may not beparticularly linear.

According to the above-described reference voltage generating circuit 7according to the nineteenth embodiment, by generating the correctingcurrent I_(COMP) by the non-linear correcting circuit 72 to be fed backto the BGR core circuit 71, it is possible to further reduce thetemperature dependence of the output voltage V_(BGR). Further, it ispossible to reduce the value of the resistance R6 compared with a twentyfirst embodiment to be described later.

The temperature correction method in the non-linear correcting circuit72 may also be applied to the BGR circuits having the differenttopologies. Further, by forming the current mirror circuit (MP11 andMP12) of the non-linear correcting circuit 72 to have a cascodeconfiguration if there is a room in an operating voltage, or byinserting the degeneration resistances on the source sides thereof as inFIG. 39 described above, it is possible to prevent current mismatching.

Twentieth Embodiment

FIG. 46 is a circuit diagram illustrating an example of a referencevoltage generating circuit according to a twentieth embodiment.

In FIG. 46, the same reference numerals are given to the same componentsand the like as in the reference voltage generating circuit 7 accordingto the nineteenth embodiment, and detailed description thereof will notbe shown.

A reference voltage generating circuit 8 shown in FIG. 46 includes a BGRcore circuit 71 and a non-linear correcting circuit 73. The non-linearcorrecting circuit 73 has a configuration in which the resistance R6 ofthe non-linear correcting circuit 72 according to the twentiethembodiment is divided, a resistance R62 is provided between an emitterterminal of the bipolar transistor Q5 and the ground node and aresistance R61 is provided between an emitter terminal of the bipolartransistor Q6 and the ground node. The correcting current I_(COMP)generated by the correcting circuit 73 is expressed as Formula 73 whenR₆₁=R₆₂.

$\begin{matrix}( {{Formula}{\mspace{11mu} \;}73} ) & \; \\{{Formula}\mspace{14mu} 73} & \; \\{I_{COMP} = \{ \begin{matrix}{0\mspace{14mu} ( {V_{BGR} \leq {2V_{{{BE}\; 5},7}}} )} \\{\frac{V_{BGR} - {2V_{{{BE}\; 5},7}}}{R_{62}}( {V_{BGR} \geq {2V_{{{BE}\; 5},7}}} )}\end{matrix} } & ( {{Formula}\mspace{14mu} 73} )\end{matrix}$

According to the reference voltage generating circuit 8 according to thetwentieth embodiment, in a similar way to the reference voltagegenerating circuit 7, it is possible to further reduce the temperaturedependence of the output voltage V_(BGR).

The temperature correction method in the non-linear correcting circuit73 may also be applied to the BGR circuits having the differenttopologies. Further, by forming the current mirror circuit (MP11 andMP12) of the non-linear correcting circuit 73 to have a cascodeconfiguration if there is a room in an operating voltage, or byinserting the degeneration resistances on the source sides thereof as inFIG. 39 described above, it is possible to prevent current mismatching.

Twenty First Embodiment

FIG. 47 is a circuit diagram illustrating an example of a referencevoltage generating circuit according to a twenty first embodiment.

In FIG. 47, the same reference numerals are given to the same componentsand the like as in the reference voltage generating circuit 7 accordingto the nineteenth embodiment, and detailed description thereof will notbe shown.

A reference voltage generating circuit 9 shown in FIG. 47 includes a BGRcore circuit 71 and a non-linear correcting circuit 74. The non-linearcorrecting circuit 74 includes a bipolar transistor Q10 in which anoutput of the BGR core circuit is input to a base side thereof; abipolar transistor Q9 that is diode-connected and is connected to anemitter side of the bipolar transistor Q10 on a collector side thereof;a resistance R6 that is provided between an emitter terminal of thebipolar transistor Q9 and the ground node; and a current mirror circuit(MP11 and MP12) that generates a correcting current I_(COMP). Thebipolar transistors Q9 and Q10 are stacked at two stages for the samepurpose as in the non-linear correcting circuit 72 according to thetwentieth embodiment.

According to the reference voltage generating circuit 9 according to thetwenty first embodiment, in a similar way to the reference voltagegenerating circuit 7, it is possible to further reduce the temperaturedependence of the output voltage V_(BGR). Further, since the non-linearcorrecting circuit 74 does not have the cascode configuration of thecurrent mirror circuit, differently from the non-linear correctingcircuits 72 and 73, and the number of elements is small, it is possibleto further reduce the chip area.

The temperature correction method in the non-linear correcting circuit74 may also be applied to the BGR circuits having the differenttopologies. Further, by forming the current mirror circuit (MP11 andMP12) of the non-linear correcting circuit 73 to have a cascodeconfiguration if there is a room in an operating voltage, or byinserting the degenerating resistances on the source sides thereof as inFIG. 39 described above, it is possible to prevent current mismatching.

Twenty Second Embodiment

FIG. 48 is a circuit diagram illustrating an example of a referencevoltage generating circuit according to a twenty second embodiment.

A reference voltage generating circuit 11 shown in FIG. 48 includes aBGR core circuit 75 and a non-linear correcting circuit 76. The BGR corecircuit 75 includes a pair of NPN bipolar transistors Q1 and Q2 that areconnected in common at base terminals thereof; a resistance R20 that isconnected in common at one end thereof, is connected to the baseterminal of the bipolar transistor Q2, and is provided between anemitter side of the bipolar transistor Q1 and an emitter side of thebipolar transistor Q2; a resistance R23 that is divided into aresistance R23A and a resistance R23B and is provided between theemitter terminals of the bipolar transistors Q1 and Q2 and the groundnode; MOS transistors MP13 to MP15 that form a current mirror circuit;an NPN bipolar transistor Q11 that is diode-connected and is connectedto a ground node on an emitter side thereof; and a resistance R33 thatis provided between the base terminals of the bipolar transistors Q1 andQ2 and a collector terminal of the bipolar transistor Q11. Further, thebipolar transistor Q11 forms a non-linear correcting circuit 76 incooperation with a resistance R34 and a PNP bipolar transistor Q11P. Inthe non-linear correcting circuit 76, the resistance R34 is connected toa connection node of a drain terminal of the MOS transistor MP3 and thebase terminals of the bipolar transistors Q1 and Q2 at one end thereof.Further, the bipolar transistor Q11P is connected to a base terminal ofthe bipolar transistor Q11 at a base terminal thereof, is connected tothe other end of the resistance R4 at an emitter terminal thereof, andis connected to the connection node of the resistances R11 and R12 at acollector terminal thereof.

The correcting current I_(COMP) generated by the correcting circuit 75is expressed as Formula 74.

$\begin{matrix}{\mspace{79mu} ( {{Formula}{\mspace{11mu} \;}74} )} & \; \\{\mspace{79mu} {{Formula}\mspace{14mu} 74}} & \; \\{I_{COMP} = \{ \begin{matrix}{0\mspace{14mu} ( {V_{BGR} \leq ( {V_{{BE}\; 11} + V_{{BE}\; 11P}} )} )} \\{\frac{V_{BGR} - ( {V_{{BE}\; 11} + V_{{BE}\; 11P}} }{R_{34}}( {V_{BGR} \geq ( {V_{{BE}\; 11} + V_{{BE}\; 11P}} )} )}\end{matrix} } & ( {{Formula}\mspace{14mu} 74} )\end{matrix}$

In the case of the BGR core circuit 75, since the output voltage V_(BGR)is about 1.2 V, by forming the bipolar transistors Q11 and Q11P in thedouble-stage structure, a base-emitter voltage VBE becomes two times,and thus, a preferable correcting current I_(COMP) is generated. Here,VBE is set to be two times in consideration of a case where VBE of thebipolar transistor is about 0.7 V at low temperature and about 0.35 V athigh temperature.

According to the reference voltage generating circuit 11 according tothe twenty second embodiment, in a similar way to the reference voltagegenerating circuit 7, it is possible to further reduce the temperaturedependence of the output voltage V. Further, by using a configuration inwhich elements that form the BGR core circuit 75 and the non-linearcorrecting circuit 76 are shared, it is possible to reduce the number ofelements, and to reduce the chip area.

The temperature correction method in the non-linear correcting circuit75 may also be applied to the BGR circuits having the differenttopologies. Further, by forming the current mirror circuit (MP1, MP2 andMP3) of the non-linear correcting circuit 75 to have a cascodeconfiguration if there is a room in an operating voltage, or byinserting the degenerating resistances on the source sides thereof as inFIG. 39 described above, it is possible to prevent current mismatching.

Hereinbefore, the invention made by the inventors has been specificallydescribed, but the invention is not limited thereto, and variousmodifications may be made in a range without departing from the spiritof the invention.

For example, the types of combination of the BGR core circuit and thenon-linear correcting circuit shown in the first to twenty secondembodiments are not limited to the above examples, and if the correctingcurrent I_(COMP) may be appropriately fed back to the BGR core circuit,different combinations may be used to perform the non-linear correction.For example, in the reference voltage generating circuit 2 according tothe second embodiment, any one of the BGR core circuits 10I to 10Q maybe applied instead of the BGR core circuit 10A.

Further, an example in which the start-up circuit 30 and the low passfilter 60 are added to the reference voltage generating circuit 1 isshown in the first embodiment, but the invention is not limited thereto.That is, the start-up circuit 30 and the low pass filter 60 may also beapplied to the reference voltage generating circuits according to theother embodiments.

INDUSTRIAL APPLICABILITY

The present invention relates to a voltage generating circuit, andparticularly, may be widely applied to a reference voltage generatingcircuit in a semiconductor integrated circuit.

EXPLANATION OF REFERENCE NUMERALS

-   1 to 9, and 11 Reference voltage generating circuit-   10, 10A to 10Q, 71, 75 BGR core circuit-   20, 20A to 20C, 72 to 74 Non-linear correcting circuit-   A, A1 to A3 Amplifier-   300 Straight line for comparison-   30 Start-up circuit-   41 Power supply control section-   42 Reference buffer-   43 Main regulator-   44 Sub regulator-   45 CPU-   46 Register-   47 Non-volatile storage element-   48 Peripheral circuit-   49 Input and output circuit-   50 Power supply circuit-   51 AD converter-   52 DA converter-   60 LPF (low pass filter)-   70 Regulator circuit (Reference current source)-   100, 101 Semiconductor integrated circuit device (system LSI)-   51 Power supply circuit-   52 Temperature sensor-   53 AD converter-   54 Reference voltage generating circuit

What is claimed is:
 1. A voltage generating circuit comprising: avoltage generating section that generates a voltage obtained by adding avoltage difference between base-emitter voltages of two bipolartransistors that are operated at different current densities and aforward voltage of a PN junction at a predetermined ratio and outputsthe result; and a correcting circuit that generates a correcting currentbased on a difference between the voltage generated by the voltagegenerating section and the forward voltage of the PN junction and feedsback the correcting current to the voltage generating section.
 2. Thevoltage generating circuit according to claim 1, wherein the correctingcircuit includes: a first bipolar transistor that is connected to afirst electric potential node through a first resistance element at anemitter terminal thereof and is diode-connected; a second bipolartransistor that is connected to a collector side of the first bipolartransistor at an emitter terminal thereof and is connected to an outputside of the voltage generating section at a collector terminal and abase terminal thereof that are diodeconnected; and a current outputsection that outputs a current based on a current that flows in thefirst resistance element.
 3. The voltage generating circuit according toclaim 1, wherein the correcting circuit includes: a first bipolartransistor that is connected to a first electric potential node througha first resistance element at an emitter terminal thereof and isdiode-connected; a second bipolar transistor that is connected to acollector side of the first bipolar transistor at an emitter terminalthereof and is connected to an output side of the voltage generatingsection at a base terminal thereof; and a current mirror circuit thatoutputs a current based on a current that flows on a collector side ofthe second bipolar transistor.
 4. The voltage generating circuitaccording to claim 1, wherein the voltage generating section includes: athird bipolar transistor that is connected to the first electricpotential node through a second resistance element at a collectorterminal thereof; a fourth bipolar transistor that has an emitter arealarger than the emitter area of the third bipolar transistor and isconnected to the first electric potential node through a thirdresistance element at a collector terminal thereof; a fourth resistanceelement that is provided between an emitter terminal of the thirdbipolar transistor and an emitter terminal of the fourth bipolartransistor; and a fifth resistance element that is provided between theemitter terminal of the second bipolar transistor and a second electricpotential node, wherein the correcting current is fed back to the fifthresistance element.
 5. The voltage generating circuit according to claim1, further comprising: a correcting circuit that generates a correctingcurrent based on a difference between the voltage generated by theoutput section and a gate-source voltage of a MOS transistor that isoperated in a sub threshold region and feeds back the correcting currentto the current generating section.
 6. The voltage generating circuitaccording to claim 5, wherein the correcting circuit includes: a firstMOS transistor that includes a gate terminal disposed on an output sideof the output section; a fourth resistance element that is connected tothe first electric potential node at one end thereof; one or a pluralityof second MOS transistors that is provided between a source terminal ofthe first MOS transistor and the other end of the fourth resistanceelement and includes a gate terminal and a drain terminal at the sameelectric potential; and a current mirror section that outputs a currentbased on a current that flows on a drain side of the first MOStransistor.
 7. A voltage generating circuit comprising: a currentgenerating section that generates a current obtained by adding a currentbased on a voltage difference between base-emitter voltages of twobipolar transistors having different emitter areas and a current basedon a forward voltage of a PN junction, and an output section thatconverts an input current into a voltage and outputs the convertedvoltage, wherein the current generating section includes a first bipolartransistor that includes an emitter terminal disposed on a firstelectric potential node side; a second bipolar transistor that has anemitter area larger than an emitter area of the first bipolartransistor, includes an emitter terminal at the same electric potentialas in the emitter terminal of the first bipolar transistor and includesa base terminal disposed on a collector side of the first bipolartransistor; a first resistance element that is disposed on the collectorside of the first bipolar transistor at one end thereof and is disposedon a base side of the first bipolar transistor at the other end thereof;a second resistance element that is disposed on a collector side of thesecond bipolar transistor at one end thereof and is connected to theother end of the first resistance element at the other end thereof; athird resistance element that is provided between a base terminal of thefirst bipolar transistor and the first electric potential node; anamplifier that receives, as inputs, a voltage on the collector side ofthe first bipolar transistor and a voltage on the collector side of thesecond bipolar transistor and outputs a voltage based on a voltagedifference between two input voltages; and a voltage-current convertingsection that receives, as an input, the output voltage of the amplifier,converts the received voltage into a current and supplies the convertedcurrent to a connection node of the first resistance element and thesecond resistance element and to the output section, wherein the outputsection is a fourth resistance element that is connected to the firstelectric potential node at one end thereof and receives an input of acurrent at the other end thereof, further comprising: a correctingcircuit that generates a correcting current based on a differencebetween the voltage generated by the output section and the forwardvoltage of the PN junction and feeds back the correcting current to thefourth resistance element.